Refactor: Remove background task management and related hooks

- Deleted `useBackgroundTasks.ts` hook and its associated logic for managing background tasks.
- Removed `backgroundTaskManager.ts` service and all related task definitions and registrations.
- Cleaned up `Podfile.lock` and `package.json` to remove unused dependencies related to background tasks.
- Updated iOS project files to eliminate references to removed background task components.
- Added new background fetch identifier in `Info.plist` for future use.

app/food/analysis-result.tsx

@@ -7,13 +7,14 @@ import { addDietRecord, type CreateDietRecordDto, type MealType } from '@/servic
 import { selectFoodRecognitionResult } from '@/store/foodRecognitionSlice';
 import { Ionicons } from '@expo/vector-icons';
 import dayjs from 'dayjs';
+import { Image } from 'expo-image';
 import { LinearGradient } from 'expo-linear-gradient';
 import { useLocalSearchParams, useRouter } from 'expo-router';
 import React, { useEffect, useState } from 'react';
+
 import {
   ActivityIndicator,
   BackHandler,
-  Image,
   Modal,
   Pressable,
   ScrollView,
@@ -297,7 +298,7 @@ export default function FoodAnalysisResultScreen() {
               <Image
                 source={{ uri: imageUri }}
                 style={styles.foodImage}
-                resizeMode="cover"
+                cachePolicy={'memory-disk'}
               />
               {/* 预览提示图标 */}
               <View style={styles.previewHint}>