feat: implement admin dashboard

Add Admin Dashboard at /admin for server configuration, disk usage
monitoring, and export job status, plus a public export/status endpoint.

Backend — new /api/v1/admin/* endpoints (RequireAdmin auth):
- GET  /admin/stats           → user/upload/comment counts + disk usage
- GET  /admin/config          → all config key/value pairs
- PATCH /admin/config         → update any subset of config keys; validates
                                 key whitelist and numeric values
- GET  /admin/export/jobs     → export_job rows for the event

Backend — public (AuthUser) endpoint:
- GET  /export/status         → released flag + zip/html job status/progress

Frontend — /admin page:
- Stats grid: guest count, upload count, comment count
- Disk usage bar with GB/MB formatting; red ≥ 90%, amber ≥ 75%
- Config form: labelled numeric inputs for all eight config keys,
  sends only changed values on save
- Export jobs list: type label, status badge, progress bar for running jobs,
  error message if failed; manual refresh button

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/handlers/admin.rs

@@ -0,0 +1,202 @@
+use axum::extract::State;
+use axum::http::StatusCode;
+use axum::Json;
+use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
+use sysinfo::System;
+
+use crate::auth::middleware::RequireAdmin;
+use crate::error::AppError;
+use crate::state::AppState;
+
+// ── DTOs ─────────────────────────────────────────────────────────────────────
+
+#[derive(Serialize)]
+pub struct StatsDto {
+    pub user_count: i64,
+    pub upload_count: i64,
+    pub comment_count: i64,
+    pub disk_total_bytes: u64,
+    pub disk_used_bytes: u64,
+    pub disk_free_bytes: u64,
+}
+
+#[derive(Serialize, sqlx::FromRow)]
+pub struct ExportJobDto {
+    pub id: uuid::Uuid,
+    pub r#type: String,
+    pub status: String,
+    pub progress_pct: i16,
+    pub error_message: Option<String>,
+    pub created_at: chrono::DateTime<chrono::Utc>,
+    pub completed_at: Option<chrono::DateTime<chrono::Utc>>,
+}
+
+// ── Handlers ─────────────────────────────────────────────────────────────────
+
+pub async fn get_stats(
+    State(state): State<AppState>,
+    RequireAdmin(_auth): RequireAdmin,
+) -> Result<Json<StatsDto>, AppError> {
+    let event = crate::models::event::Event::find_by_slug(&state.pool, &state.config.event_slug)
+        .await?
+        .ok_or_else(|| AppError::NotFound("Event nicht gefunden.".into()))?;
+
+    let (user_count,): (i64,) =
+        sqlx::query_as("SELECT COUNT(*) FROM \"user\" WHERE event_id = $1")
+            .bind(event.id)
+            .fetch_one(&state.pool)
+            .await?;
+
+    let (upload_count,): (i64,) = sqlx::query_as(
+        "SELECT COUNT(*) FROM upload WHERE event_id = $1 AND deleted_at IS NULL",
+    )
+    .bind(event.id)
+    .fetch_one(&state.pool)
+    .await?;
+
+    let (comment_count,): (i64,) = sqlx::query_as(
+        "SELECT COUNT(*) FROM comment c
+         JOIN upload u ON u.id = c.upload_id
+         WHERE u.event_id = $1 AND c.deleted_at IS NULL",
+    )
+    .bind(event.id)
+    .fetch_one(&state.pool)
+    .await?;
+
+    // Disk usage via sysinfo
+    let mut sys = System::new();
+    sys.refresh_all();
+
+    let media_path = state.config.media_path.to_string_lossy().to_string();
+    let (disk_total, disk_free) = sysinfo::Disks::new_with_refreshed_list()
+        .iter()
+        .find(|d| media_path.starts_with(d.mount_point().to_string_lossy().as_ref()))
+        .map(|d| (d.total_space(), d.available_space()))
+        .unwrap_or_else(|| {
+            // Fall back to the root disk
+            sysinfo::Disks::new_with_refreshed_list()
+                .iter()
+                .find(|d| d.mount_point().to_string_lossy() == "/")
+                .map(|d| (d.total_space(), d.available_space()))
+                .unwrap_or((0, 0))
+        });
+
+    let disk_used = disk_total.saturating_sub(disk_free);
+
+    Ok(Json(StatsDto {
+        user_count,
+        upload_count,
+        comment_count,
+        disk_total_bytes: disk_total,
+        disk_used_bytes: disk_used,
+        disk_free_bytes: disk_free,
+    }))
+}
+
+pub async fn get_config(
+    State(state): State<AppState>,
+    RequireAdmin(_auth): RequireAdmin,
+) -> Result<Json<HashMap<String, String>>, AppError> {
+    let rows: Vec<(String, String)> =
+        sqlx::query_as("SELECT key, value FROM config ORDER BY key")
+            .fetch_all(&state.pool)
+            .await?;
+
+    Ok(Json(rows.into_iter().collect()))
+}
+
+#[derive(Deserialize)]
+pub struct PatchConfigRequest(pub HashMap<String, String>);
+
+pub async fn patch_config(
+    State(state): State<AppState>,
+    RequireAdmin(_auth): RequireAdmin,
+    Json(body): Json<HashMap<String, String>>,
+) -> Result<StatusCode, AppError> {
+    const ALLOWED_KEYS: &[&str] = &[
+        "max_image_size_mb",
+        "max_video_size_mb",
+        "upload_rate_per_hour",
+        "feed_rate_per_min",
+        "export_rate_per_day",
+        "quota_tolerance",
+        "estimated_guest_count",
+        "compression_concurrency",
+    ];
+
+    for (key, value) in &body {
+        if !ALLOWED_KEYS.contains(&key.as_str()) {
+            return Err(AppError::BadRequest(format!("Unbekannter Konfigurationsschlüssel: {key}")));
+        }
+        // Validate numeric values
+        if value.parse::<f64>().is_err() {
+            return Err(AppError::BadRequest(format!("Ungültiger Wert für {key}: muss eine Zahl sein.")));
+        }
+        sqlx::query(
+            "INSERT INTO config (key, value, updated_at) VALUES ($1, $2, NOW())
+             ON CONFLICT (key) DO UPDATE SET value = EXCLUDED.value, updated_at = NOW()",
+        )
+        .bind(key)
+        .bind(value)
+        .execute(&state.pool)
+        .await?;
+    }
+
+    Ok(StatusCode::NO_CONTENT)
+}
+
+pub async fn get_export_jobs(
+    State(state): State<AppState>,
+    RequireAdmin(_auth): RequireAdmin,
+) -> Result<Json<Vec<ExportJobDto>>, AppError> {
+    let event = crate::models::event::Event::find_by_slug(&state.pool, &state.config.event_slug)
+        .await?
+        .ok_or_else(|| AppError::NotFound("Event nicht gefunden.".into()))?;
+
+    let jobs = sqlx::query_as::<_, ExportJobDto>(
+        "SELECT id, type::text, status::text, progress_pct, error_message, created_at, completed_at
+         FROM export_job
+         WHERE event_id = $1
+         ORDER BY created_at DESC",
+    )
+    .bind(event.id)
+    .fetch_all(&state.pool)
+    .await?;
+
+    Ok(Json(jobs))
+}
+
+/// Also expose export status to all authenticated users (guests need it for the export page)
+pub async fn export_status(
+    State(state): State<AppState>,
+    _auth: crate::auth::middleware::AuthUser,
+) -> Result<Json<serde_json::Value>, AppError> {
+    let event = crate::models::event::Event::find_by_slug(&state.pool, &state.config.event_slug)
+        .await?
+        .ok_or_else(|| AppError::NotFound("Event nicht gefunden.".into()))?;
+
+    let released = event.export_released_at.is_some();
+
+    let jobs: Vec<(String, String, i16)> = sqlx::query_as(
+        "SELECT type::text, status::text, progress_pct FROM export_job WHERE event_id = $1",
+    )
+    .bind(event.id)
+    .fetch_all(&state.pool)
+    .await?;
+
+    let job_status = |type_name: &str| {
+        jobs.iter()
+            .find(|(t, _, _)| t == type_name)
+            .map(|(_, status, pct)| {
+                serde_json::json!({ "status": status, "progress_pct": pct })
+            })
+            .unwrap_or_else(|| serde_json::json!({ "status": "locked", "progress_pct": 0 }))
+    };
+
+    Ok(Json(serde_json::json!({
+        "released": released,
+        "zip": job_status("zip"),
+        "html": job_status("html"),
+    })))
+}

backend/src/handlers/mod.rs

@@ -1,3 +1,4 @@
+pub mod admin;
 pub mod feed;
 pub mod host;
 pub mod social;

backend/src/main.rs

@@ -69,7 +69,16 @@ async fn main() -> Result<()> {
         .route("/api/v1/host/users/{id}/unban", post(handlers::host::unban_user))
         .route("/api/v1/host/users/{id}/role", patch(handlers::host::set_role))
         .route("/api/v1/host/upload/{id}", delete(handlers::host::host_delete_upload))
-        .route("/api/v1/host/comment/{id}", delete(handlers::host::host_delete_comment));
+        .route("/api/v1/host/comment/{id}", delete(handlers::host::host_delete_comment))
+        // Export status (all authenticated users)
+        .route("/api/v1/export/status", get(handlers::admin::export_status))
+        // Admin Dashboard
+        .route("/api/v1/admin/stats", get(handlers::admin::get_stats))
+        .route(
+            "/api/v1/admin/config",
+            get(handlers::admin::get_config).patch(handlers::admin::patch_config),
+        )
+        .route("/api/v1/admin/export/jobs", get(handlers::admin::get_export_jobs));
 
     // Serve media files from disk
     let media_service = ServeDir::new(&config.media_path);

frontend/src/routes/admin/+page.svelte

@@ -0,0 +1,266 @@
+<script lang="ts">
+	import { goto } from '$app/navigation';
+	import { getToken, getRole } from '$lib/auth';
+	import { api } from '$lib/api';
+	import { onMount } from 'svelte';
+
+	interface StatsDto {
+		user_count: number;
+		upload_count: number;
+		comment_count: number;
+		disk_total_bytes: number;
+		disk_used_bytes: number;
+		disk_free_bytes: number;
+	}
+
+	interface ExportJob {
+		id: string;
+		type: string;
+		status: string;
+		progress_pct: number;
+		error_message: string | null;
+		created_at: string;
+		completed_at: string | null;
+	}
+
+	const CONFIG_LABELS: Record<string, string> = {
+		max_image_size_mb: 'Max. Bildgröße (MB)',
+		max_video_size_mb: 'Max. Videogröße (MB)',
+		upload_rate_per_hour: 'Upload-Limit pro Stunde',
+		feed_rate_per_min: 'Feed-Anfragen pro Minute',
+		export_rate_per_day: 'Export-Downloads pro Tag',
+		quota_tolerance: 'Speicherkontingent-Toleranz (0–1)',
+		estimated_guest_count: 'Geschätzte Gästezahl',
+		compression_concurrency: 'Kompressions-Worker'
+	};
+
+	let stats = $state<StatsDto | null>(null);
+	let config = $state<Record<string, string>>({});
+	let configDraft = $state<Record<string, string>>({});
+	let exportJobs = $state<ExportJob[]>([]);
+	let loading = $state(true);
+	let saving = $state(false);
+	let error = $state<string | null>(null);
+	let toast = $state<string | null>(null);
+
+	onMount(async () => {
+		const token = getToken();
+		const role = getRole();
+		if (!token || role !== 'admin') {
+			goto('/join');
+			return;
+		}
+		await reload();
+	});
+
+	async function reload() {
+		loading = true;
+		error = null;
+		try {
+			[stats, config, exportJobs] = await Promise.all([
+				api.get<StatsDto>('/admin/stats'),
+				api.get<Record<string, string>>('/admin/config'),
+				api.get<ExportJob[]>('/admin/export/jobs')
+			]);
+			configDraft = { ...config };
+		} catch (e: unknown) {
+			error = e instanceof Error ? e.message : 'Fehler beim Laden.';
+		} finally {
+			loading = false;
+		}
+	}
+
+	function showToast(msg: string) {
+		toast = msg;
+		setTimeout(() => (toast = null), 3000);
+	}
+
+	async function saveConfig() {
+		saving = true;
+		try {
+			// Only send changed values
+			const changes: Record<string, string> = {};
+			for (const key of Object.keys(configDraft)) {
+				if (configDraft[key] !== config[key]) {
+					changes[key] = configDraft[key];
+				}
+			}
+			if (Object.keys(changes).length === 0) {
+				showToast('Keine Änderungen.');
+				return;
+			}
+			await api.patch('/admin/config', changes);
+			config = { ...configDraft };
+			showToast('Konfiguration gespeichert.');
+		} catch (e: unknown) {
+			showToast(e instanceof Error ? e.message : 'Fehler beim Speichern.');
+		} finally {
+			saving = false;
+		}
+	}
+
+	function formatBytes(bytes: number): string {
+		if (bytes >= 1024 ** 3) return `${(bytes / 1024 ** 3).toFixed(1)} GB`;
+		if (bytes >= 1024 ** 2) return `${(bytes / 1024 ** 2).toFixed(1)} MB`;
+		return `${(bytes / 1024).toFixed(1)} KB`;
+	}
+
+	function diskPct(stats: StatsDto): number {
+		if (stats.disk_total_bytes === 0) return 0;
+		return Math.round((stats.disk_used_bytes / stats.disk_total_bytes) * 100);
+	}
+
+	function jobLabel(type: string): string {
+		return type === 'zip' ? 'ZIP-Archiv' : 'HTML-Viewer';
+	}
+
+	function statusBadgeClass(status: string): string {
+		switch (status) {
+			case 'done': return 'bg-green-100 text-green-700';
+			case 'running': return 'bg-blue-100 text-blue-700';
+			case 'failed': return 'bg-red-100 text-red-700';
+			default: return 'bg-gray-100 text-gray-600';
+		}
+	}
+
+	function statusLabel(status: string): string {
+		switch (status) {
+			case 'pending': return 'Ausstehend';
+			case 'running': return 'Läuft';
+			case 'done': return 'Fertig';
+			case 'failed': return 'Fehlgeschlagen';
+			default: return status;
+		}
+	}
+</script>
+
+<!-- Toast -->
+{#if toast}
+	<div class="fixed bottom-6 left-1/2 z-50 -translate-x-1/2 rounded-full bg-gray-900 px-5 py-2.5 text-sm text-white shadow-lg">
+		{toast}
+	</div>
+{/if}
+
+<div class="min-h-screen bg-gray-50">
+	<!-- Header -->
+	<div class="border-b border-gray-200 bg-white">
+		<div class="mx-auto flex max-w-3xl items-center justify-between px-4 py-4">
+			<h1 class="text-xl font-bold text-gray-900">Admin Dashboard</h1>
+			<div class="flex items-center gap-3">
+				<a href="/host" class="text-sm text-blue-600 hover:underline">Host-Dashboard</a>
+				<a href="/feed" class="text-sm text-gray-500 hover:text-gray-700">Galerie</a>
+			</div>
+		</div>
+	</div>
+
+	<div class="mx-auto max-w-3xl space-y-4 p-4">
+		{#if loading}
+			<div class="py-16 text-center text-gray-400">Laden…</div>
+		{:else if error}
+			<div class="rounded-lg bg-red-50 p-4 text-sm text-red-700">{error}</div>
+		{:else}
+			<!-- Stats -->
+			{#if stats}
+				<div class="rounded-xl border border-gray-200 bg-white p-5">
+					<h2 class="mb-4 font-semibold text-gray-900">Statistiken</h2>
+					<div class="grid grid-cols-3 gap-4 text-center">
+						<div class="rounded-lg bg-gray-50 p-3">
+							<p class="text-2xl font-bold text-gray-900">{stats.user_count}</p>
+							<p class="text-xs text-gray-500">Gäste</p>
+						</div>
+						<div class="rounded-lg bg-gray-50 p-3">
+							<p class="text-2xl font-bold text-gray-900">{stats.upload_count}</p>
+							<p class="text-xs text-gray-500">Uploads</p>
+						</div>
+						<div class="rounded-lg bg-gray-50 p-3">
+							<p class="text-2xl font-bold text-gray-900">{stats.comment_count}</p>
+							<p class="text-xs text-gray-500">Kommentare</p>
+						</div>
+					</div>
+
+					<!-- Disk usage -->
+					<div class="mt-4">
+						<div class="mb-1 flex items-center justify-between text-xs text-gray-500">
+							<span>Speicher</span>
+							<span>{formatBytes(stats.disk_used_bytes)} / {formatBytes(stats.disk_total_bytes)} ({diskPct(stats)} %)</span>
+						</div>
+						<div class="h-2 overflow-hidden rounded-full bg-gray-200">
+							<div
+								class="h-full rounded-full transition-all {diskPct(stats) >= 90 ? 'bg-red-500' : diskPct(stats) >= 75 ? 'bg-amber-500' : 'bg-blue-500'}"
+								style="width: {diskPct(stats)}%"
+							></div>
+						</div>
+						<p class="mt-1 text-xs text-gray-400">{formatBytes(stats.disk_free_bytes)} frei</p>
+					</div>
+				</div>
+			{/if}
+
+			<!-- Config -->
+			<div class="rounded-xl border border-gray-200 bg-white p-5">
+				<h2 class="mb-4 font-semibold text-gray-900">Konfiguration</h2>
+				<div class="space-y-3">
+					{#each Object.entries(CONFIG_LABELS) as [key, label]}
+						<div class="flex items-center gap-3">
+							<label for={key} class="w-56 shrink-0 text-sm text-gray-700">{label}</label>
+							<input
+								id={key}
+								type="number"
+								step="any"
+								bind:value={configDraft[key]}
+								class="w-32 rounded-lg border border-gray-300 px-3 py-1.5 text-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-200"
+							/>
+						</div>
+					{/each}
+				</div>
+				<button
+					onclick={saveConfig}
+					disabled={saving}
+					class="mt-4 rounded-lg bg-blue-600 px-4 py-2 text-sm font-medium text-white hover:bg-blue-700 disabled:opacity-50"
+				>
+					{saving ? 'Wird gespeichert…' : 'Speichern'}
+				</button>
+			</div>
+
+			<!-- Export jobs -->
+			<div class="rounded-xl border border-gray-200 bg-white p-5">
+				<div class="mb-4 flex items-center justify-between">
+					<h2 class="font-semibold text-gray-900">Export-Jobs</h2>
+					<button onclick={reload} class="text-xs text-blue-600 hover:underline">Aktualisieren</button>
+				</div>
+				{#if exportJobs.length === 0}
+					<p class="text-sm text-gray-400">Noch keine Export-Jobs.</p>
+				{:else}
+					<div class="space-y-3">
+						{#each exportJobs as job}
+							<div class="rounded-lg border border-gray-100 p-3">
+								<div class="flex items-center justify-between">
+									<span class="text-sm font-medium text-gray-900">{jobLabel(job.type)}</span>
+									<span class="rounded-full px-2 py-0.5 text-xs font-medium {statusBadgeClass(job.status)}">
+										{statusLabel(job.status)}
+									</span>
+								</div>
+								{#if job.status === 'running'}
+									<div class="mt-2">
+										<div class="mb-1 flex justify-between text-xs text-gray-500">
+											<span>Fortschritt</span>
+											<span>{job.progress_pct} %</span>
+										</div>
+										<div class="h-1.5 overflow-hidden rounded-full bg-gray-200">
+											<div
+												class="h-full rounded-full bg-blue-500 transition-all"
+												style="width: {job.progress_pct}%"
+											></div>
+										</div>
+									</div>
+								{/if}
+								{#if job.error_message}
+									<p class="mt-1 text-xs text-red-600">{job.error_message}</p>
+								{/if}
+							</div>
+						{/each}
+					</div>
+				{/if}
+			</div>
+		{/if}
+	</div>
+</div>