feat(profile): add data storage settings screen with cache management

Add DataStorageScreen for managing media cache and storage:
- Display cache statistics (image/video/audio counts and sizes)
- Show AsyncStorage usage information
- Add clear all cache functionality
- Add cleanup expired cache option (7 days threshold)
- Add storage usage breakdown by category
- Add "Last cleaned" timestamp display

Also fix MediaCacheManager to skip native cache operations on web platform:
- Return original URI directly on web without caching
- Skip directory creation on web
- Skip file existence checks on web
- Skip startup and periodic cleanup on web

src/infrastructure/cache/MediaCacheManager.ts

@@ -6,6 +6,7 @@
 
 import { File, Paths } from 'expo-file-system';
 import AsyncStorage from '@react-native-async-storage/async-storage';
+import { Platform } from 'react-native';
 import {
   MediaType,
   CleanupTrigger,
@@ -102,13 +103,15 @@ export class MediaCacheManager {
       // 加载缓存记录
       await this.loadCacheRecords();
       
-      // 启动时清理
-      if (this.policy.cleanupOnStart) {
+      // 启动时清理 (非web平台)
+      if (this.policy.cleanupOnStart && Platform.OS !== 'web') {
         await this.cleanup(CleanupTrigger.STARTUP);
       }
       
-      // 启动定期清理
-      this.startPeriodicCleanup();
+      // 启动定期清理 (非web平台)
+      if (Platform.OS !== 'web') {
+        this.startPeriodicCleanup();
+      }
       
       this.isInitialized = true;
     } catch (error) {
@@ -121,6 +124,8 @@ export class MediaCacheManager {
    * 确保缓存目录存在
    */
   private async ensureDirectories(): Promise<void> {
+    if (Platform.OS === 'web') return;
+    
     try {
       const dirs = [getImageDir(), getVideoDir(), getAudioDir()];
       for (const dir of dirs) {
@@ -168,6 +173,8 @@ export class MediaCacheManager {
    * 检查文件是否存在
    */
   private async checkFileExists(path: string): Promise<boolean> {
+    if (Platform.OS === 'web') return false;
+    
     try {
       const file = new File(path);
       return await file.exists;
@@ -199,6 +206,10 @@ export class MediaCacheManager {
       size?: number;
     } = {}
   ): Promise<string> {
+    if (Platform.OS === 'web') {
+      return uri;
+    }
+
     const { conversationId, messageId, size = 0 } = options;
     
     // 生成唯一键