feat: 集成后台任务管理功能及相关组件

- 新增后台任务管理器，支持任务的注册、执行和状态监控
- 实现自定义Hook，简化后台任务的使用和管理
- 添加示例任务，包括数据同步、健康数据更新和通知检查等
- 更新文档，详细描述后台任务系统的实现和使用方法
- 优化相关组件，确保用户体验和界面一致性

app/(tabs)/statistics.tsx

@@ -13,6 +13,7 @@ import { Colors } from '@/constants/Colors';
 import { getTabBarBottomPadding } from '@/constants/TabBar';
 import { useAppDispatch, useAppSelector } from '@/hooks/redux';
 import { useAuthGuard } from '@/hooks/useAuthGuard';
+import { useBackgroundTasks } from '@/hooks/useBackgroundTasks';
 import { useColorScheme } from '@/hooks/useColorScheme';
 import { calculateNutritionSummary, getDietRecords, NutritionSummary } from '@/services/dietRecords';
 import { fetchDailyMoodCheckins, selectLatestMoodRecordByDate } from '@/store/moodSlice';
@@ -131,7 +132,7 @@ export default function ExploreScreen() {
   // 营养数据状态
   const [nutritionSummary, setNutritionSummary] = useState<NutritionSummary | null>(null);
   const [isNutritionLoading, setIsNutritionLoading] = useState(false);
-
+  const { registerTask } = useBackgroundTasks();
   // 心情相关状态
   const dispatch = useAppDispatch();
   const [isMoodLoading, setIsMoodLoading] = useState(false);
@@ -299,6 +300,21 @@ export default function ExploreScreen() {
     }, [selectedIndex])
   );
 
+  useEffect(() => {
+        // 注册任务
+    registerTask({
+      id: 'health-data-task',
+      name: 'health-data-task',
+      handler: async () => {
+        try {
+          await loadHealthData();
+        } catch (error) {
+          console.error('健康数据任务执行失败:', error);
+        }
+      },
+    });
+  }, []);
+
   // 日期点击时，加载对应日期数据
   const onSelectDate = (index: number, date: Date) => {
     setSelectedIndex(index);