feat(admin): runtime-editable crawler & analysis config in the dashboard

Move crawler and analysis configuration out of boot-only env vars and into
a DB-backed, admin-editable surface applied live without a restart.

- New `app_settings` table (migration 0026) holds one JSONB row per group;
  env vars seed it on first boot, then the DB is the source of truth.
- `settings.rs` adds serializable Crawler/Analysis DTOs with env-base +
  DB-overlay conversion and field-level validation; env-only/secret fields
  (browser, proxy, TOR, vision API key, PHPSESSID) are never persisted.
- `GET/PUT /api/v1/admin/settings/{crawler,analysis}` (RequireAdmin,
  cookie-only, CSRF-guarded): GET returns the editable DTO + a read-only
  env-managed view + prompt defaults; PUT validates (422 + per-field
  details), persists + audits in one tx, then gracefully respawns the
  affected daemon via a Supervisor.
- AppState swaps the crawler control/resync handles and analysis enable
  gate behind shared runtime cells so reloads take effect with no restart;
  a boot-time spawn failure is logged rather than aborting startup.
- Make the three vision prompts and sampling temperature configurable
  (defaults preserved); cookie_domain is admin-editable too.
- Frontend: tabbed /admin/settings page with grouped fieldsets, prompt
  reset-to-default, env-managed read-only panel, save-&-apply confirm, and
  per-field validation; typed client + ApiError.details.
- Bump version 0.79.1 -> 0.80.0.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/lib/api/admin.ts

@@ -556,3 +556,110 @@ export type AnalysisEvent =
 export function analysisStatusStreamUrl(): string {
     return apiUrl('/v1/admin/analysis/status/stream');
 }
+
+// ---- runtime settings (crawler + analysis) ---------------------------------
+
+/** Operationally-safe, admin-editable crawler settings. Host/infra and
+ *  session/secret fields are managed via environment and surfaced read-only
+ *  in {@link CrawlerEnvOnly}. */
+export type CrawlerSettings = {
+    daemon_enabled: boolean;
+    daily_at: string; // "HH:MM"
+    tz: string; // IANA
+    idle_timeout_secs: number;
+    chapter_workers: number;
+    retention_days: number;
+    start_url: string | null;
+    rate_ms: number;
+    cdn_host: string | null;
+    cdn_rate_ms: number;
+    cookie_domain: string | null;
+    user_agent: string | null;
+    download_allowlist: string[];
+    allow_any_host: boolean;
+    max_image_bytes: number;
+    manga_limit: number;
+    job_timeout_secs: number;
+    metadata_max_consecutive_failures: number;
+    browser_restart_threshold: number;
+};
+
+/** Read-only view of crawler fields managed via environment. */
+export type CrawlerEnvOnly = {
+    browser_mode: string;
+    browser_args: string[];
+    proxy: string | null;
+    tor_control_url: string | null;
+    tor_credentials_configured: boolean;
+    session_configured: boolean;
+};
+
+export type CrawlerSettingsResponse = {
+    editable: CrawlerSettings;
+    env_only: CrawlerEnvOnly;
+};
+
+/** Admin-editable analysis settings. Prompts are `null` to mean "use the
+ *  compiled default" (see {@link PromptDefaults}). The vision API key is
+ *  env-only and never returned. */
+export type AnalysisSettings = {
+    enabled: boolean;
+    workers: number;
+    endpoint: string;
+    model: string;
+    request_timeout_secs: number;
+    job_timeout_secs: number;
+    max_tokens: number;
+    max_pixels: number;
+    min_slice_height: number;
+    slice_overlap: number;
+    tall_aspect_threshold: number;
+    max_slices: number;
+    max_image_bytes: number;
+    response_format: 'json_schema' | 'json_object' | 'none';
+    frequency_penalty: number;
+    temperature: number;
+    system_prompt: string | null;
+    ocr_prompt: string | null;
+    grounding_prompt: string | null;
+};
+
+export type PromptDefaults = {
+    system_prompt: string;
+    ocr_prompt: string;
+    grounding_prompt: string;
+};
+
+export type AnalysisSettingsResponse = {
+    editable: AnalysisSettings;
+    env_only: { api_key_configured: boolean };
+    prompt_defaults: PromptDefaults;
+};
+
+export async function getCrawlerSettings(): Promise<CrawlerSettingsResponse> {
+    return request<CrawlerSettingsResponse>('/v1/admin/settings/crawler');
+}
+
+export async function updateCrawlerSettings(
+    settings: CrawlerSettings
+): Promise<CrawlerSettingsResponse> {
+    return request<CrawlerSettingsResponse>('/v1/admin/settings/crawler', {
+        method: 'PUT',
+        headers: { 'content-type': 'application/json' },
+        body: JSON.stringify(settings)
+    });
+}
+
+export async function getAnalysisSettings(): Promise<AnalysisSettingsResponse> {
+    return request<AnalysisSettingsResponse>('/v1/admin/settings/analysis');
+}
+
+export async function updateAnalysisSettings(
+    settings: AnalysisSettings
+): Promise<AnalysisSettingsResponse> {
+    return request<AnalysisSettingsResponse>('/v1/admin/settings/analysis', {
+        method: 'PUT',
+        headers: { 'content-type': 'application/json' },
+        body: JSON.stringify(settings)
+    });
+}