feat: Add services for managing trip-related data

- Implement EmergencyService for handling emergency contacts per trip.
- Create GuestFlagService to manage guest mode flags for trips.
- Introduce NotificationService with local notification capabilities.
- Add OfflineFlagService for managing offline caching flags.
- Develop PackingService for shared packing lists per trip.
- Implement ReminderService for managing reminders/to-dos per trip.
- Create SosService for dispatching SOS events to a backend.
- Add StorageService with album image upload functionality.
- Implement TransportService for managing transport segments per trip.
- Create TripChecklistService for storing and retrieving trip checklists.
- Add TripDocumentService for persisting trip documents metadata.

test: Add unit tests for new services

- Implement tests for AlbumService, BudgetService, EmergencyService, GuestFlagService, PackingService, ReminderService, SosService, TransportService, TripChecklistService, and TripDocumentService.
- Ensure tests cover adding, loading, deleting, and handling corrupted payloads for each service.

lib/services/notification_service.dart

@@ -6,6 +6,8 @@ import 'package:firebase_auth/firebase_auth.dart';
 import 'package:firebase_messaging/firebase_messaging.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_local_notifications/flutter_local_notifications.dart';
+import 'package:timezone/data/latest_all.dart' as tz;
+import 'package:timezone/timezone.dart' as tz;
 import 'package:travel_mate/components/account/group_expenses_page.dart';
 import 'package:travel_mate/components/activities/activities_page.dart';
 import 'package:travel_mate/components/group/chat_group_content.dart';
@@ -50,6 +52,8 @@ class NotificationService {
     if (_isInitialized) return;
 
     await _requestPermissions();
+    tz.initializeTimeZones();
+    tz.setLocalLocation(tz.getLocation('UTC'));
 
     const androidSettings = AndroidInitializationSettings(
       '@mipmap/ic_launcher',
@@ -411,4 +415,75 @@ class NotificationService {
       payload: json.encode(message.data),
     );
   }
+
+  /// Shows a local push notification with a custom [title] and [body].
+  ///
+  /// Used for recap/reminder notifications when on-device scheduling is desired.
+  Future<void> showLocalRecap({
+    required String title,
+    required String body,
+  }) async {
+    const androidDetails = AndroidNotificationDetails(
+      'recap_channel',
+      'Recap quotidien',
+      channelDescription: 'Notifications de récap voyage',
+      importance: Importance.max,
+      priority: Priority.high,
+    );
+    const iosDetails = DarwinNotificationDetails();
+    const details = NotificationDetails(
+      android: androidDetails,
+      iOS: iosDetails,
+    );
+
+    await _localNotifications.show(
+      DateTime.now().millisecondsSinceEpoch ~/ 1000,
+      title,
+      body,
+      details,
+    );
+  }
+
+  /// Schedules a local reminder notification at [dueAt] with [title]/[body].
+  Future<void> scheduleReminder({
+    required String id,
+    required String title,
+    required String body,
+    required DateTime dueAt,
+  }) async {
+    try {
+      final int notifId = id.hashCode & 0x7fffffff;
+      final scheduled = tz.TZDateTime.from(dueAt, tz.local);
+
+      const androidDetails = AndroidNotificationDetails(
+        'reminder_channel',
+        'Rappels voyage',
+        channelDescription: 'Notifications des rappels/to-dos',
+        importance: Importance.high,
+        priority: Priority.high,
+      );
+      const iosDetails = DarwinNotificationDetails();
+      const details = NotificationDetails(
+        android: androidDetails,
+        iOS: iosDetails,
+      );
+
+      await _localNotifications.zonedSchedule(
+        notifId,
+        title,
+        body,
+        scheduled,
+        details,
+        androidScheduleMode: AndroidScheduleMode.exactAllowWhileIdle,
+      );
+    } catch (e) {
+      LoggerService.error('Failed to schedule reminder', error: e);
+    }
+  }
+
+  /// Cancels a scheduled reminder notification by [id].
+  Future<void> cancelReminder(String id) async {
+    final notifId = id.hashCode & 0x7fffffff;
+    await _localNotifications.cancel(notifId);
+  }
 }