first commit

lib/providers/background_sync_provider.dart

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+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import '../services/background_sync_service.dart';
+
+// BackgroundSyncService Provider
+final backgroundSyncServiceProvider = Provider<BackgroundSyncService>((ref) {
+  final service = BackgroundSyncService();
+  
+  // 当 Provider 被销毁时，停止服务
+  ref.onDispose(() {
+    service.stop();
+  });
+  
+  return service;
+});
+
+// 后台同步状态 Provider
+final backgroundSyncStatusProvider = StateProvider<bool>((ref) {
+  return false;
+});
+