fix: address multiple code audit findings

- CORS: replace wildcard with explicit origin list from CORS_ORIGINS env
- Auth: enforce strong defaults, JWT blacklist (RevokedToken model), login rate limiting
- Auth: validate password length before bcrypt (72-byte limit)
- Scheduler: single-threaded worker to mitigate SQLite write contention
- Scheduler: graceful shutdown (wait=True)
- Snapshots: add prune_snapshots() with configurable retention count
- Storage: isolate localStorage keys via VITE_APP_KEY prefix
- Config: add cors_origins, login_rate_limit, snapshot_retention_count settings

frontend/src/assets/main.css

@@ -91,6 +91,11 @@ img {
   margin: 0 auto;
 }
 
+.shell-page.shell-page-fluid {
+  width: 100%;
+  max-width: none;
+}
+
 .page-section {
   display: grid;
   gap: 1.25rem;