Stage 11: polish, cross-cutting concerns & hardening

- 11.1 MainLayout health indicator: warning MessageBar when fail2ban offline
- 11.2 formatDate utility + TimezoneProvider + GET /api/setup/timezone
- 11.3 Responsive sidebar: auto-collapse <640px, media query listener
- 11.4 PageFeedback (PageLoading/PageError/PageEmpty), BanTable updated
- 11.5 prefers-reduced-motion: disable sidebar transition
- 11.6 WorldMap ARIA: role/tabIndex/aria-label/onKeyDown for countries
- 11.7 Health transition logging (fail2ban_came_online/went_offline)
- 11.8 Global handlers: Fail2BanConnectionError/ProtocolError -> 502
- 11.9 379 tests pass, 82% coverage, ruff+mypy+tsc+eslint clean
- Timezone endpoint: setup_service.get_timezone, 5 new tests

backend/app/tasks/blocklist_import.py

@@ -104,7 +104,7 @@ def reschedule(app: FastAPI) -> None:
     asyncio.ensure_future(_do_reschedule())
 
 
-def _apply_schedule(app: FastAPI, config: Any) -> None:  # type: ignore[override]
+def _apply_schedule(app: FastAPI, config: Any) -> None:
     """Add or replace the APScheduler cron/interval job for the given config.
 
     Args: