refactor(heartbeat): refresh devices every 2min instead of pinging /auth/me

apps/mobile_app/lib/providers/legacy_heartbeat_service.dart

@@ -2,20 +2,21 @@ import 'dart:async';
 
 import 'package:dio/dio.dart';
 import 'package:flutter/foundation.dart';
-import 'package:sf_infrastructure/sf_infrastructure.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart' show WidgetRef;
+import 'package:sf_shared/sf_shared.dart';
 
 class LegacyHeartbeatService {
   LegacyHeartbeatService({
-    required SaveFamilyRepository repository,
+    required WidgetRef ref,
     required void Function() onUnauthorized,
-  }) : _repository = repository,
+  }) : _ref = ref,
        _onUnauthorized = onUnauthorized;
 
-  final SaveFamilyRepository _repository;
+  final WidgetRef _ref;
   final void Function() _onUnauthorized;
   Timer? _timer;
 
-  static const _interval = Duration(minutes: 3);
+  static const _interval = Duration(minutes: 2);
 
   void start() {
     if (_timer != null) return;
@@ -32,8 +33,8 @@ class LegacyHeartbeatService {
 
   Future<void> _beat() async {
     try {
-      await _repository.get<dynamic>('/auth/me');
-      debugPrint('[LegacyHeartbeat] /auth/me => OK');
+      await _ref.read(legacyDevicesProvider.notifier).refresh();
+      debugPrint('[LegacyHeartbeat] devices refreshed');
     } catch (e) {
       debugPrint('[LegacyHeartbeat] error: $e');
       if (e is DioException && e.response?.statusCode == 401) {

apps/mobile_app/lib/save_family_app.dart

@@ -60,7 +60,7 @@ class SaveFamilyAppState extends ConsumerState<SaveFamilyApp>
 
     if (isLegacyMode) {
       _legacyHeartbeat = LegacyHeartbeatService(
-        repository: GetIt.I<SaveFamilyRepository>(),
+        ref: ref,
         onUnauthorized: () {
           clearSessionData();
           appRouter.go(AppRoutes.legacyLogin);