fix: 补全运动服务 Provider

- 添加 exerciseServiceProvider（之前缺失导致运动页加载失败）

health_app/lib/providers/data_providers.dart

@@ -2,6 +2,10 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'auth_provider.dart';
 import '../services/health_service.dart';
 
+final exerciseServiceProvider = Provider<ExerciseService>((ref) {
+  return ExerciseService(ref.watch(apiClientProvider));
+});
+
 /// 健康数据服务
 final healthServiceProvider = Provider<HealthService>((ref) {
   return HealthService(ref.watch(apiClientProvider));