fix(rereview): close export-flip race + queue-dedup reload regression

Adversarial re-review of the persona-audit + audit-followup rounds (6411747..)
found one HIGH and one MED regression plus LOW gaps. All fixed with coverage.

HIGH — export stale-keepsake resurrected by an open_event race
  A reopen landing in the window between a *current* export worker's finalize_job
  and its ready-flag flip cleared export_released_at + the ready flags but left the
  export_job row `done` at the same release_seq. The seq-guarded flip then still
  matched and re-set export_{zip,html}_ready=TRUE on a pre-reopen snapshot; the next
  re-release read that stale TRUE and skipped regeneration (`if ready { continue }`),
  serving a keepsake missing every upload from the reopen window — the exact data
  loss migration 012 exists to prevent. Both ready-flip UPDATEs are now additionally
  anchored on `export_released_at IS NOT NULL`, so a landed reopen makes the flip a
  no-op and the re-release regenerates cleanly.

MED — queue dedup broke for reloaded items
  loadQueue rebuilt QueueItems from IndexedDB without copying lastModified, which the
  new addToQueue dedup keys on. A file re-selected after a page reload / PWA relaunch
  missed the duplicate check and uploaded twice. Rehydration now carries lastModified
  (extracted to a pure, tested entryToQueueItem helper).

LOW
  - diashow: clear the upload-processed debounce timer in onDestroy (no stray
    post-unmount /feed fetch).
  - USER_JOURNEYS §9.5: document the reconnect-delta ban replay (hidden_user_ids /
    uploads_hidden_at, migration 013), not just the live user-hidden SSE.
  - e2e api-client: drop the misleading hide_uploads param from banUser — the backend
    takes no body and always hides; strip the dead boolean at all call sites.

Tests
  - Extract isReversibleLock (the terminal-403 KEEP-vs-PURGE-blob discriminator) into a
    pure exported helper + unit tests, so the data-loss-critical branch is covered
    without an XHR harness.
  - entryToQueueItem unit tests lock the lastModified-carry regression.
  - Document the export flip-race guard in the reopen/re-release spec (the sub-ms
    finalize↔flip interleave isn't deterministically forceable with fast fixtures;
    covered by the SQL guard + the end-to-end completeness test).

Verified: backend 40 tests, frontend 44 unit tests, svelte-check 0 errors,
e2e 156 passed / 1 skipped on chromium-desktop.

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

e2e/specs/07-adversarial/authorization-deep.spec.ts

@@ -82,7 +82,7 @@ test.describe('Adversarial — deep authorization', () => {
 
   test('banned user cannot toggle a like', async ({ api, host, guest }) => {
     const target = await guest('BannedLike');
-    await api.banUser(host.jwt, target.userId, false);
+    await api.banUser(host.jwt, target.userId);
 
     const res = await fetch(`${BASE}/api/v1/upload/00000000-0000-0000-0000-000000000000/like`, {
       method: 'POST',
@@ -93,7 +93,7 @@ test.describe('Adversarial — deep authorization', () => {
 
   test('banned user cannot post a comment', async ({ api, host, guest }) => {
     const target = await guest('BannedComment');
-    await api.banUser(host.jwt, target.userId, false);
+    await api.banUser(host.jwt, target.userId);
 
     const res = await fetch(`${BASE}/api/v1/upload/00000000-0000-0000-0000-000000000000/comments`, {
       method: 'POST',
@@ -105,7 +105,7 @@ test.describe('Adversarial — deep authorization', () => {
 
   test('banned user can still read the feed (read-only access preserved)', async ({ api, host, guest }) => {
     const target = await guest('BannedRead');
-    await api.banUser(host.jwt, target.userId, false);
+    await api.banUser(host.jwt, target.userId);
 
     const res = await fetch(`${BASE}/api/v1/feed`, {
       headers: { Authorization: `Bearer ${target.jwt}` },