feat: 集成expo-background-task和expo-task-manager，重构后台任务管理，添加健康提醒功能，优化任务执行逻辑

ios/digitalpilates/AppDelegate.swift

@@ -1,7 +1,6 @@
 import Expo
 import React
 import ReactAppDependencyProvider
-import TSBackgroundFetch
 
 @UIApplicationMain
 public class AppDelegate: ExpoAppDelegate {
@@ -22,8 +21,6 @@ public class AppDelegate: ExpoAppDelegate {
     reactNativeFactory = factory
     bindReactNativeFactory(factory)
 
-    TSBackgroundFetch.sharedInstance().didFinishLaunching();
-
 #if os(iOS) || os(tvOS)
     window = UIWindow(frame: UIScreen.main.bounds)
     factory.startReactNative(