feat(04-01): Android config, NotificationService, DAO queries, timezone init, ARB strings

- Add flutter_local_notifications ^21.0.0, timezone ^0.11.0, flutter_timezone ^1.0.8 to pubspec.yaml
- Set compileSdk=35, enable core library desugaring in build.gradle.kts
- Add POST_NOTIFICATIONS, RECEIVE_BOOT_COMPLETED permissions and boot receivers to AndroidManifest.xml
- Create NotificationService singleton with initialize, requestPermission, scheduleDailyNotification, cancelAll
- Add getOverdueAndTodayTaskCount and getOverdueTaskCount one-shot queries to DailyPlanDao
- Initialize timezone and NotificationService in main.dart before runApp
- Add 7 notification-related ARB strings to app_de.arb
- All 72 existing tests pass

lib/main.dart

@@ -1,9 +1,17 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_timezone/flutter_timezone.dart';
+import 'package:timezone/data/latest_all.dart' as tz;
+import 'package:timezone/timezone.dart' as tz;
 
 import 'package:household_keeper/app.dart';
+import 'package:household_keeper/core/notifications/notification_service.dart';
 
-void main() {
+void main() async {
   WidgetsFlutterBinding.ensureInitialized();
+  tz.initializeTimeZones();
+  final timeZoneName = await FlutterTimezone.getLocalTimezone();
+  tz.setLocalLocation(tz.getLocation(timeZoneName));
+  await NotificationService().initialize();
   runApp(const ProviderScope(child: App()));
 }