Merge branch 'fix/deploy-unattended-blockers' into main

Two independent lines of production hardening diverged at 7d0334b and attacked
overlapping problems. Neither was a superset, so this is a merge of substance
rather than a fast-forward: every conflict was resolved on the merits, and the
losing side's intent was re-checked against the winner rather than assumed.

MIGRATIONS. The branch's 021/022/023 collided with main's already-DEPLOYED
021_hashtag_counts_respect_bans and 022_client_upload_idempotency. Renumbered to
023/024/025 in a prior commit — main's versions are applied in production, so
their version numbers are immutable and the branch's had to move. Verified by
running the full sqlx::test suite, which applies the whole chain from scratch.

RESOLVED IN MAIN'S FAVOUR (the branch would have regressed these):
  * upload-queue.ts wholesale — the branch's copy has ZERO client_upload_id
    references, so taking it would have silently destroyed end-to-end upload
    idempotency, the one thing standing between a lost response and a duplicate
    photo charged twice against the guest's quota.
  * maintenance.rs supervisor — the branch replaced it with a bare tokio::spawn,
    where one panic silently stops session pruning, media reclaim, the temp
    sweep and both HashMap prunes, permanently and with no log line.
  * The decode-budget probe on spawn_blocking, not inline on the async runtime.
  * feed/+page.svelte's 8s debounce + jitter + max-wait + hidden-tab deferral,
    against the branch's naive 800ms — at 100 guests the branch's version walks
    straight into the per-user feed rate limit.
  * db.rs pool tuning, /uploaders, and the docker-compose deployment story.
  * ONE /health, still DB-backed. The branch's split (dependency-free liveness +
    DB-backed readiness) is defensible, but a constant-"ok" /health is the exact
    defect faea555 fixed and verified live, its motive (Caddy's boot gate) is
    already covered by app depends_on db: service_healthy, and the two handlers
    were the same SELECT 1 under two names.

TAKEN FROM THE BRANCH:
  * The large-PNG OOM guard and its bounded-retry counter (023). Together these
    turn a single upload that can OOM-kill a 1G container into a bounded failure
    instead of an infinite restart loop under `restart: unless-stopped`.
  * 024_feed_scalar_counts — the feed no longer aggregates the whole event per
    page. Pure SQL; column names, order and types are unchanged by design.
  * The admin-lockout fix: look the admin up BY ROLE, never by name. 025 also
    frees any guest already squatting on a reserved name.
  * PIN lockout tier ordering, bounded caption/hashtag reads, SSE ticket caps,
    PoolTimedOut -> 503 + Retry-After, and the ffmpeg stderr drain.
  * backfill_video_posters, which main lacked entirely.
  * TempFileGuard, plus sweep_orphan_originals wired into main's SUPERVISED loop
    (not the branch's bare one) — it reclaims final-named originals whose commit
    never happened, a class main's .tmp-only sweep structurally cannot see.
  * shouldAbortForStall, hand-ported into main's upload-queue.ts since that file
    was resolved to main. Widens the watchdog at loadend instead of disarming it,
    bounding a half-open socket at 2 minutes rather than handing the window to
    xhr.timeout (5-60 min) with the whole queue's `processing` latch held.

ALSO: RUST_LOG and EXPORT_PATH pinned in compose. The code fallback was
`debug` (a line per request, all night) and EXPORT_PATH was the one path with a
mount-shaped default that nothing validated.

Verified: cargo check --all-targets, cargo clippy (clean), 144/144 backend tests
against a live Postgres including upload_idempotency and upload_concurrency,
51/51 vitest, svelte-check 0 errors, eslint clean, vite build.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

frontend/src/lib/api.ts

@@ -46,6 +46,13 @@ async function request<T>(method: string, path: string, body?: unknown): Promise
 
 	// Abort hung requests so a dead connection surfaces as a friendly error
 	// instead of a spinner that never resolves.
+	//
+	// The timer must stay armed until the BODY has been read, not just the headers.
+	// `fetch` resolves as soon as the response head arrives, so clearing it in a `finally`
+	// around the fetch left `res.text()` below completely uncovered — and no longer
+	// abortable, since the controller had already been disarmed. An upstream that sends
+	// headers and then stalls the body (the shape of a half-dead proxy, or of the pool
+	// saturation this same release adds shedding for) hung that call forever.
 	const controller = new AbortController();
 	const timer = setTimeout(() => controller.abort(), TIMEOUT_MS);
 
@@ -57,6 +64,26 @@ async function request<T>(method: string, path: string, body?: unknown): Promise
 			body: body !== undefined ? JSON.stringify(body) : undefined,
 			signal: controller.signal
 		});
+	} catch (e) {
+		clearTimeout(timer);
+		if (e instanceof DOMException && e.name === 'AbortError') {
+			throw new ApiError(0, 'timeout', 'Zeitüberschreitung – bitte erneut versuchen.');
+		}
+		throw new ApiError(0, 'network', 'Netzwerkfehler – bitte Verbindung prüfen.');
+	}
+
+	if (res.status === 204) {
+		// Must clear on this path too, or every no-content request (logout, delete, like)
+		// leaks a live 20 s timer.
+		clearTimeout(timer);
+		return undefined as T;
+	}
+
+	// A 5xx behind a proxy (or a crash page) can return HTML, not JSON — parsing
+	// it directly would throw an opaque SyntaxError. Read text, parse defensively.
+	let raw: string;
+	try {
+		raw = await res.text();
 	} catch (e) {
 		if (e instanceof DOMException && e.name === 'AbortError') {
 			throw new ApiError(0, 'timeout', 'Zeitüberschreitung – bitte erneut versuchen.');
@@ -66,13 +93,6 @@ async function request<T>(method: string, path: string, body?: unknown): Promise
 		clearTimeout(timer);
 	}
 
-	if (res.status === 204) {
-		return undefined as T;
-	}
-
-	// A 5xx behind a proxy (or a crash page) can return HTML, not JSON — parsing
-	// it directly would throw an opaque SyntaxError. Read text, parse defensively.
-	const raw = await res.text();
 	let data: { error?: string; message?: string } | unknown = null;
 	if (raw) {
 		try {