refactor(database): migrate to new modular database layer and unify data access

- Remove legacy database.ts, LocalDataSource.ts, and MessageRepository.ts
- Create new src/database/ module with messageRepository, userCacheRepository, conversationRepository, and groupCacheRepository
- Update all consumers to import from @/database instead of services/database
- Add web platform blur handling for modal components to fix focus issues
- Flatten SystemMessageItem and NotificationsScreen styles for consistent design
- Add draggable slider in ChatSettingsScreen and dynamic font size support
- Introduce 9 new chat color themes
- Add profile screens for about, terms, and privacy policy with navigation routes
- Add policy links to login and registration screens
- Fix post share URL format from /posts/ to /post/

src/data/repositories/PostRepository.ts

@@ -4,7 +4,7 @@
  */
 
 import { ApiDataSource, apiDataSource } from '../datasources/ApiDataSource';
-import { LocalDataSource, localDataSource } from '../datasources/LocalDataSource';
+import { localDataSource } from '@/database';
 import { PostMapper } from '../mappers/PostMapper';
 import type { Post, PostImage, PostStatus } from '../../core/entities/Post';
 import { createPost } from '../../core/entities/Post';
@@ -79,13 +79,12 @@ interface CachedPost {
 
 export class PostRepository implements IPostRepository {
   private api: ApiDataSource;
-  private localDb: LocalDataSource;
+  private localDb = localDataSource;
   private memoryCache: Map<string, { post: Post; timestamp: number }> = new Map();
-  private readonly CACHE_TTL = 5 * 60 * 1000; // 5分钟缓存过期时间
+  private readonly CACHE_TTL = 5 * 60 * 1000;
 
-  constructor(api: ApiDataSource, localDb: LocalDataSource) {
+  constructor(api: ApiDataSource) {
     this.api = api;
-    this.localDb = localDb;
   }
 
   // ==================== 私有辅助方法 ====================
@@ -575,5 +574,5 @@ export class PostRepository implements IPostRepository {
 
 // ==================== 单例导出 ====================
 
-export const postRepository = new PostRepository(apiDataSource, localDataSource);
+export const postRepository = new PostRepository(apiDataSource);
 export default postRepository;