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/_layout.tsx

@@ -2,14 +2,14 @@ import { DefaultTheme, ThemeProvider } from '@react-navigation/native';
 import { useFonts } from 'expo-font';
 import { Stack } from 'expo-router';
 import { StatusBar } from 'expo-status-bar';
-import 'react-native-reanimated';
-import 'react-native-gesture-handler';
 import { GestureHandlerRootView } from 'react-native-gesture-handler';
+import 'react-native-reanimated';
 
 import PrivacyConsentModal from '@/components/PrivacyConsentModal';
 import { useAppDispatch, useAppSelector } from '@/hooks/redux';
 import { useColorScheme } from '@/hooks/useColorScheme';
 import { clearAiCoachSessionCache } from '@/services/aiCoachSession';
+import { backgroundTaskManager } from '@/services/backgroundTaskManager';
 import { store } from '@/store';
 import { rehydrateUser, setPrivacyAgreed } from '@/store/userSlice';
 import React from 'react';
@@ -31,7 +31,18 @@ function Bootstrapper({ children }: { children: React.ReactNode }) {
       setUserDataLoaded(true);
     };
 
+    const initializeBackgroundTasks = async () => {
+      try {
+        await backgroundTaskManager.initialize();
+
+        console.log('后台任务管理器初始化成功');
+      } catch (error) {
+        console.error('后台任务管理器初始化失败:', error);
+      }
+    };
+
     loadUserData();
+    initializeBackgroundTasks();
     // 冷启动时清空 AI 教练会话缓存
     clearAiCoachSessionCache();
   }, [dispatch]);
@@ -96,6 +107,7 @@ export default function RootLayout() {
                 <Stack.Screen name="legal/privacy-policy" options={{ headerShown: true, title: '隐私政策' }} />
                 <Stack.Screen name="article/[id]" options={{ headerShown: false }} />
                 <Stack.Screen name="nutrition/records" options={{ headerShown: false }} />
+                <Stack.Screen name="background-tasks-test" options={{ headerShown: true, title: '后台任务测试' }} />
                 <Stack.Screen name="+not-found" />
               </Stack>
               <StatusBar style="dark" />