fix: gate uploads on keepsake headroom, and close five unattended-event gaps

The box is 2 vCPU / 4 GB / 40 GB, not the 4 vCPU / 8 GB / 80 GB that the audit,
the committed comments and README's sizing section all assumed. That correction
is what the first change is about; the rest are the remaining pre-event items.

THE ARCHIVE COULD BECOME UNBUILDABLE WHILE UPLOADS KEPT SUCCEEDING

`required_free_bytes` is `media × 1.1 × 2` — the ZIP and the HTML viewer are each
gallery-sized — and the export preflight also wants DISK_RESERVE_BYTES on top. The
upload gate, though, only refused below a FLAT 10 GB reserve. On 40 GB that let
uploads run to ~25 GB of media while a release needed `2.2 × 25 + 10` = 65 GB free.
Every upload in that band succeeded and the keepsake could then never be built: the
product's entire promise, failing silently at the end of the night with nobody there.

The gate now enforces the invariant that actually matters — never accept an upload
that would make the keepsake unbuildable — sharing `required_free_bytes` with the
preflight so the two cannot drift into disagreeing about the same question. Uploads
stop at ~8 GB of media on this disk, with a German message naming the cause.
Refusing the 1001st photo beats losing all 1000.

`media_total.rs` backs it: SUM(user.total_upload_bytes) over ~100 rows, cached 5s,
rather than `estimate_export_bytes`'s join across every upload. It counts hidden and
banned users' bytes, which the export excludes — skew in the SAFE direction, so the
gate closes marginally early rather than late. Fails open on a query error.

A test pins the gate against the preflight across the whole gallery-size range, and
a second asserts the per-user floor alone would over-commit the volume — i.e. that
the global gate is what must bind.

THE WATCHDOG ABORTED HEALTHY UPLOADS EVERY TIME A PHONE WAS POCKETED

`Date.now()` advances while a backgrounded phone is frozen but `setInterval` does
not, so the first tick after a screen lock read the whole sleep as silence and
aborted — re-sending a video from byte zero and burning one of five PERMANENT
auto-attempts. The interval is now its own suspension detector: a tick that arrives
125s late for a 5s schedule credits that window back, because a period the watchdog
could not observe is not evidence of silence.

Chosen over a `visibilitychange` listener, which only covers causes that fire that
event — a throttled-but-visible tab, a closed lid and an occluded window all freeze
timers without one — and which would have needed module state, an SSR guard and a
teardown for strictly less coverage. `performance.now()` was rejected because Safari
pauses it across system sleep on some paths and Chrome does not.

The credit buys one fresh window, not immunity: a socket iOS reaped while
backgrounded still aborts ~90s after resume rather than hanging for `xhr.timeout`
(5-60 min) with the queue's `processing` latch held.

Two latent leaks found while in there: `xhr.abort()` on a request already in
readyState DONE emits no `abort` event, so `settle()` never ran and the interval
re-aborted every 5s forever while `activeUploads` kept a stale entry (the ✕ button
silently stopped working); and a synchronous throw from `xhr.send` — a blob whose
backing store the OS purged — leaked the same way. Both closed.

OKLCH MADE THE DELETE BUTTON INVISIBLE ON SAMSUNG'S DEFAULT BROWSER

red/amber/green were never in the @theme block and fell through to Tailwind v4's
`oklch()` defaults, which Safari <15.4, Chrome <111 and Samsung Internet <22 cannot
parse: `var(--color-red-600)` is then invalid at computed-value time, `background-color`
falls back to transparent, and `.btn-danger` renders white text on nothing. Pinned to
Tailwind's own defaults gamut-mapped to sRGB by Lightning CSS — the converter already
in this pipeline — so modern browsers render exactly what they render today. Verified
against seven hex fallbacks it had already emitted for the /alpha forms. rose and teal
(avatar chips) had the same leak. The app CSS goes from 40 oklch declarations to 0.

Also fixes `--color-purple-950`, which was simply missing: `dark:bg-purple-950/50` on
the host dashboard was rendering default violet on EVERY browser, off-brand.

The keepsake viewer only picks this up on a rebuild, so its committed artefact is
rebuilt here too — still single-file, still zero external references.

A BRICKED BOOT LOOKED LIKE A SPINNER FOREVER

With `ssr = false` the page is empty until the bundle mounts, so a chunk 404 after a
redeploy or a dead uplink left the guest on the boot spinner with no message, no
reload control, and in a standalone PWA no URL bar. A 15s timeout in the existing
nonce'd IIFE (no CSP change) swaps in German copy and a reload button. Deliberately a
timeout rather than feature detection: a SyntaxError in the bundle is invisible to any
capability check. Plus a <noscript>, since there was nothing at all to see without JS.

EVERY 4xx WAS INVISIBLE AT ANY LOG LEVEL

tower_http counts 4xx as a success, so it logs at DEBUG while production runs at info.
If guests spend the evening hitting 429s or 413s, the post-event logs said nothing.
Now one WARN per client error; 5xx excluded because Internal already logs its source
chain and the pool-exhaustion 503 logs at construction.

A DEAD FRONTEND SERVED A BLANK 502

`handle_errors 5xx` with an inline German page (the caddy service mounts only the
Caddyfile, so there is no volume to ship a static file through). Verified empirically
against this config, not from documentation: an upstream 404 through `reverse_proxy`
still arrives as untouched `application/json`, and only a dial failure renders the
page. That mattered — the keepsake download navigates a hidden iframe and DEPENDS on a
real 404/429 arriving, and swallowing those would have been worse than the blank 502.

CONFIG CORRECTIONS FOR THE REAL HARDWARE

DATABASE_MAX_CONNECTIONS 30 → 15: sized to 2 vCPU rather than to the guest count.
Since migration 024 a feed page costs well under a millisecond, so connections are no
longer spent waiting, and 30 backends crowd the db container's 1 GB on a 4 GB host.
COMPRESSION_WORKER_CONCURRENCY stays at 2 — the merged heavy-image permit already
serialises anything over 150 MiB, so the "two 48 MP photos" worst case that number was
sized against is unreachable; dropping to 1 would halve light-path throughput and push
more feed tiles onto full-size originals. README's sizing section rewritten for the
actual disk.

Verified: 149/149 backend tests against a live Postgres, clippy clean, 57/57 vitest,
svelte-check 0 errors, eslint clean, vite build, export-viewer rebuild, caddy validate,
compose YAML parse.

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

frontend/src/lib/upload-queue.test.ts

@@ -3,7 +3,8 @@ import {
 	classifyUploadStatus,
 	isReversibleLock,
 	entryToQueueItem,
-	shouldAbortForStall
+	shouldAbortForStall,
+	suspendedSinceLastTick
 } from './upload-queue';
 
 /**
@@ -140,4 +141,55 @@ describe('shouldAbortForStall', () => {
 		expect(shouldAbortForStall(now - 91_000, now, true)).toBe(false);
 		expect(shouldAbortForStall(now - 121_000, now, true)).toBe(true);
 	});
+
+});
+
+/**
+ * The watchdog measures SILENCE via `Date.now()`, but a backgrounded phone freezes the
+ * interval while the clock keeps running. Without crediting the un-run window back, the first
+ * tick after a screen lock reads the whole sleep as a stall and aborts a healthy upload —
+ * re-sending from byte zero and spending one of five permanent auto-attempts. That is what
+ * every phone does between shots at a party.
+ *
+ * Detecting the freeze from the tick gap (rather than from `visibilitychange`) also covers the
+ * causes that fire no visibility event at all: a throttled-but-visible tab, a closed lid, an
+ * occluded window.
+ */
+describe('suspendedSinceLastTick', () => {
+	const now = 1_000_000;
+
+	it('credits nothing for a tick that arrived on schedule', () => {
+		expect(suspendedSinceLastTick(now - 5_000, now, 5_000)).toBe(0);
+	});
+
+	it('credits nothing for ordinary timer jitter or throttling', () => {
+		expect(suspendedSinceLastTick(now - 6_900, now, 5_000)).toBe(0);
+	});
+
+	it('credits the whole frozen window when the interval did not run', () => {
+		// Screen locked ~2 minutes: a 5s interval arriving 130s late.
+		expect(suspendedSinceLastTick(now - 130_000, now, 5_000)).toBe(125_000);
+	});
+
+	it('credits nothing when the clock jumps backwards (NTP correction)', () => {
+		expect(suspendedSinceLastTick(now + 60_000, now, 5_000)).toBe(0);
+	});
+
+	it('a suspension longer than the stall ceiling does not abort a healthy upload', () => {
+		// The bug, end to end: 3 minutes suspended, interval resumes, no bytes since.
+		const lastProgressAt = now - 180_000;
+		const credited = Math.min(
+			now,
+			lastProgressAt + suspendedSinceLastTick(now - 185_000, now, 5_000)
+		);
+		expect(shouldAbortForStall(credited, now, false)).toBe(false);
+	});
+
+	it('but a socket still silent 91s AFTER resume is aborted, never left to xhr.timeout', () => {
+		// iOS reaps backgrounded sockets without firing `error`. The credit buys one fresh
+		// window, not immunity — otherwise a dead upload would hang for 5-60 minutes holding
+		// the queue's `processing` latch.
+		const resumedAt = now - 91_000;
+		expect(shouldAbortForStall(resumedAt, now, false)).toBe(true);
+	});
 });