fix(user-flow): close offline-queue, export, session, ban & realtime gaps

Comprehensive user-flow review across guest/host/admin roles, then fixes with
e2e regression guards. Highlights:

- Offline upload queue auto-resumes on reconnect: network errors keep items
  pending (not error), 4xx are terminal (no infinite retry), quota exhaustion
  returns a distinct 413; queue cap + dedup.
- Export lifecycle: release atomically locks uploads; reopen invalidates and
  re-release regenerates the keepsake; workers claim their job atomically so a
  reopen->re-release can't corrupt the ZIP; startup re-spawns interrupted
  exports.
- Sessions slide on activity (no 30-day cliff); JWT expiry deferred to the
  revocable session row; sign-out-everywhere + revoke-on-PIN-reset.
- Ban always hides content (v_feed / find_visible_media / export filter
  is_banned) but stays a read-only ban per USER_JOURNEYS §10 — sessions are
  not revoked, read access + keepsake download preserved.
- Realtime: server-clock SSE delta cursor; event-closed/opened drive the UI
  live; feed_delta rate-limited; like returns {liked, like_count} to fix
  multi-device drift; lightbox live comments; diashow delta backfill.
- Forgotten-PIN in-app request flow; simultaneous same-name join returns 409;
  quota increment is transactional; operator floor.

Adds e2e/specs/10-flow-review/ (offline resume, export integrity, deterministic
anti-race guard) and updates existing specs for the new contracts.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/src/services/maintenance.rs

@@ -44,8 +44,11 @@ pub async fn startup_recovery(pool: &PgPool) {
         Err(e) => tracing::error!("startup recovery: failed to sweep uploads: {e:#}"),
     }
 
-    // Export jobs interrupted mid-run. Mark 'failed' so the host can re-trigger.
-    // The `UNIQUE(event_id, type)` constraint would otherwise block re-release.
+    // Export jobs interrupted mid-run are marked 'failed' here so they aren't left
+    // 'running' forever. The host CANNOT re-trigger a released export (release_gallery
+    // rejects an already-released event), so `export::recover_exports` re-spawns these
+    // failed-but-released jobs from `main` once `AppState` exists (it needs the media
+    // paths + SSE sender this fn doesn't have).
     match sqlx::query(
         "UPDATE export_job
          SET status = 'failed',