feat(notifications): register FCM token with backend post-login

Adds NotificationsRemoteDatasource in sf_shared that POSTs the current
Firebase Messaging token to /notifications/push, wired into the legacy
login flow right after getUserInfo so the device can receive targeted
push notifications.

Fire-and-forget with catchError so a failure never blocks login.

modules/legacy/modules/legacy_auth/lib/src/features/login/presentation/state/login_view_model.dart

@@ -19,6 +19,7 @@ class LegacyLoginViewModel extends Notifier<LegacyLoginViewState>
     with LoginFormValidation {
   late final LegacyLoginRepository _repository;
   late final GetUserInfoUseCase _getUserInfoUseCase;
+  late final NotificationsRemoteDatasource _notifications;
   late final SfTrackingRepository _tracking;
 
   late final TextEditingController emailController;
@@ -32,6 +33,7 @@ class LegacyLoginViewModel extends Notifier<LegacyLoginViewState>
   LegacyLoginViewState build() {
     _repository = ref.read(legacyLoginRepositoryProvider);
     _getUserInfoUseCase = ref.read(getUserInfoUseCaseProvider);
+    _notifications = ref.read(notificationsRemoteDatasourceProvider);
     _tracking = ref.read(sfTrackingProvider);
 
     emailController = TextEditingController();
@@ -224,6 +226,12 @@ class LegacyLoginViewModel extends Notifier<LegacyLoginViewState>
 
       if (!ref.mounted) return;
 
+      unawaited(
+        _notifications.registerCurrentPushToken().catchError((Object e) {
+          debugPrint('[FCM] failed to register push token post-login: $e');
+        }),
+      );
+
       final hasDevices = await _repository.hasDevices();
 
       if (!ref.mounted) return;

packages/sf_shared/lib/sf_shared.dart

@@ -29,6 +29,9 @@ export 'src/providers/user_info_provider.dart';
 export 'src/domain/repositories/user_repository.dart';
 export 'src/data/repositories/user_repository_impl.dart';
 export 'src/data/datasource/user_remote_datasource_impl.dart';
+export 'src/data/datasource/notifications_remote_datasource.dart';
+export 'src/data/datasource/notifications_remote_datasource_impl.dart';
+export 'src/providers/notifications_remote_datasource_provider.dart';
 export 'src/domain/entities/beneficiary_validation_entity.dart';
 export 'src/domain/entities/transaction_beneficiary_entity.dart';
 export 'src/data/models/payout_beneficiary_model.dart';

packages/sf_shared/lib/src/data/datasource/notifications_remote_datasource.dart

@@ -0,0 +1,4 @@
+abstract class NotificationsRemoteDatasource {
+  Future<void> registerCurrentPushToken();
+  Future<void> registerPushToken(String token);
+}

packages/sf_shared/lib/src/data/datasource/notifications_remote_datasource_impl.dart

@@ -0,0 +1,34 @@
+import 'package:dio/dio.dart';
+import 'package:firebase_messaging/firebase_messaging.dart';
+import 'package:sf_infrastructure/sf_infrastructure.dart';
+
+import 'notifications_remote_datasource.dart';
+
+class NotificationsRemoteDatasourceImpl implements NotificationsRemoteDatasource {
+  NotificationsRemoteDatasourceImpl(this._repository);
+
+  final SaveFamilyRepository _repository;
+
+  @override
+  Future<void> registerCurrentPushToken() async {
+    final token = await FirebaseMessaging.instance.getToken();
+    if (token == null || token.isEmpty) return;
+    await registerPushToken(token);
+  }
+
+  @override
+  Future<void> registerPushToken(String token) async {
+    try {
+      await _repository.post<Map<String, dynamic>>(
+        '/notifications/push',
+        body: <String, dynamic>{'token': token},
+      );
+    } on DioException catch (error) {
+      final apiMsg = error.response?.data;
+      final msg = apiMsg is String
+          ? apiMsg
+          : (error.message ?? 'Error registering push token');
+      throw Exception(msg);
+    }
+  }
+}

packages/sf_shared/lib/src/providers/notifications_remote_datasource_provider.dart

@@ -0,0 +1,11 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:get_it/get_it.dart';
+import 'package:sf_infrastructure/sf_infrastructure.dart';
+import 'package:sf_shared/src/data/datasource/notifications_remote_datasource.dart';
+import 'package:sf_shared/src/data/datasource/notifications_remote_datasource_impl.dart';
+
+final notificationsRemoteDatasourceProvider =
+    Provider<NotificationsRemoteDatasource>((ref) {
+  final saveFamilyRepository = GetIt.I<SaveFamilyRepository>();
+  return NotificationsRemoteDatasourceImpl(saveFamilyRepository);
+});

packages/sf_shared/pubspec.yaml

@@ -29,6 +29,7 @@ dependencies:
   flutter_svg: ^2.2.2
   flutter_riverpod: ^3.0.3
   dio: ^5.9.2
+  firebase_messaging: ^16.1.3
   freezed_annotation: ^3.1.0
   freezed: ^3.2.3
   json_annotation: ^4.9.0