fix(storage): add disaster recovery fallback UI when LocalDb fails to open on startup #1375

Problem

In lib/main.dart (lines 32–40):

await LocalDb.initFfi();
await SyntaxHighlightService.ensureInitialized();
await ThemeController.instance.load();
await UiScaleController.instance.load();
await QueryaMotionController.instance.load();
...
runApp(const QueryaApp());

1. ThemeController, UiScaleController, and QueryaMotionController all call LocalDb.instance in their load() methods during startup before runApp is executed.
2. If querya.db fails to open (e.g. SQLite database locked by a stale process, file corruption, filesystem permission error, or WAL checkpoint failure):
   • LocalDb._doOpen() throws an unhandled exception.
   • The exception is caught by runZonedGuarded in main.dart, which only prints debugPrint('Unhandled async error: $error\n$stack').
   • runApp(const QueryaApp()) is never called.
   • The user is presented with a blank, frozen window, with no indication of why the app failed to launch and no way to recover.

Scope

• Wrap early LocalDb initialization and controller loads in a try-catch block in main.dart.
• If LocalDb fails to open, launch a minimal recovery UI (QueryaStartupRecoveryApp) that presents the error message and offers recovery actions:
  • Retry opening the database.
  • Unlock database / remove stale WAL locks.
  • Start in Safe Mode with a temporary or clean profile.
  • Export/backup existing querya.db file for diagnosis.
• Add tests verifying startup error handling when LocalDb throws.