fix(user-flow): persona-audit fixes — ban replay, locked-upload data loss, host UX, admin session

Follows the perf + security + user-flow work with a role/persona audit (guest, host,
admin, projector) and fixes across three review rounds. Highlights:

HIGH
- Ban now replays on reconnect. A ban isn't a soft-delete, and the `user-hidden` SSE has
  no replay, so a client that missed it (esp. the unattended diashow) kept cycling a
  banned user's slides. New `uploads_hidden_at` (migration 013) + `hidden_user_ids` in
  /feed/delta; feed + diashow evict those users. Applied even on a truncated delta.

MEDIUM
- Locked-upload data loss: a photo staged offline during a lock/release was purged as a
  terminal 4xx and lost when the host reopened. New reversible `uploads_locked` error code;
  the queue keeps the blob and auto-resumes on the `event-opened` SSE.
- Reopen after release now warns (ConfirmSheet) that it revokes the published keepsake.
- Host "forgotten-PIN" badge updates live (`pin-reset-requested` was broadcast but never
  in KNOWN_EVENTS / subscribed); host page also refetches on `pin-reset` so a two-host
  race can't hand out a conflicting PIN.
- Ban modal copy fixed (read-only ban, not "session ended"); Degradieren/Sperren/Entsperren
  hidden on peer-host rows for non-admins (they always 403'd).
- Host dashboard shows live keepsake generation progress / ready state + link to /export.
- Admin JWT moved to sessionStorage (§11.1) to bound exposure on shared devices.

Export generation guard (H1 from the prior round, hardened): per-(event,type) `release_seq`
(migration 012) with seq-guarded claim/finalize/mark_failed/update_progress, per-generation
temp/final paths, download follows `file_path`, prune only strictly-older generations.

LOW: diashow coalesces upload-processed (avoids self-rate-limit); event-closed reconciles
galleryReleased; /recover gains a forgot-PIN request + drops a stale cached PIN on 401;
delta `>=` tie-break + 429 retry; misc copy/labels.

Adds e2e: ban-replay, upload-lock-code, and rewrites export-reopen-rerelease with a
data-completeness test. Reconciles USER_JOURNEYS §9/§11.

Verified: cargo build clean, 40 unit tests, svelte-check 0 errors, 33 frontend unit
tests, 155 e2e passing on chromium-desktop.

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

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

@@ -231,6 +231,20 @@
 			onSseEvent('feed-delta', (data) => {
 				try {
 					const delta = JSON.parse(data) as DeltaResponse;
+					// Evict removed content FIRST and unconditionally — deletions AND ban-hides are
+					// explicit, uncapped lists, so they apply even on a truncated delta (the stale-pill
+					// refresh below only prunes page 1, so a banned user's cards beyond page 1 would
+					// otherwise linger). Replays a `user-hidden`/delete missed while the tab was hidden.
+					if (delta.deleted_ids.length) {
+						const dead = new Set(delta.deleted_ids);
+						uploads = uploads.filter((u) => !dead.has(u.id));
+						if (selectedUpload && dead.has(selectedUpload.id)) selectedUpload = null;
+					}
+					if (delta.hidden_user_ids.length) {
+						const hidden = new Set(delta.hidden_user_ids);
+						uploads = uploads.filter((u) => !hidden.has(u.user_id));
+						if (selectedUpload && hidden.has(selectedUpload.user_id)) selectedUpload = null;
+					}
 					if (delta.truncated) {
 						// Missed more than the backend delta cap while backgrounded — the
 						// delta is only the newest slice, so merging would leave a silent gap
@@ -245,10 +259,6 @@
 						const fresh = delta.uploads.filter((u) => !seen.has(u.id));
 						if (fresh.length) uploads = [...fresh, ...uploads];
 					}
-					if (delta.deleted_ids.length) {
-						const dead = new Set(delta.deleted_ids);
-						uploads = uploads.filter((u) => !dead.has(u.id));
-					}
 					// A delta reconciles new uploads and deletions, but not like/comment
 					// counts that changed on already-visible cards while we were
 					// disconnected or lagged (a `resync`). Debounced page-1 refresh merges