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/screens/message/components/ChatScreen/useChatScreen.ts

@@ -42,10 +42,7 @@ import {
   PendingChatAttachment,
 } from './types';
 import { TIME_SEPARATOR_INTERVAL, MEMBERS_PAGE_SIZE, MAX_PENDING_CHAT_IMAGES } from './constants';
-import {
-  deleteMessage as deleteMessageFromDb,
-  clearConversationMessages,
-} from '../../../../services/database';
+import { messageRepository } from '@/database';
 
 export const useChatScreen = () => {
   const getSendErrorMessage = useCallback((error: unknown, fallback: string) => {
@@ -1209,7 +1206,7 @@ export const useChatScreen = () => {
       const updatedMessages = messages.filter(m => m.id !== messageId);
       // 注意：这里我们依赖 MessageManager 的数据，所以需要通过其他方式刷新
       // 暂时只删除本地数据库
-      await deleteMessageFromDb(messageId);
+      await messageRepository.delete(messageId);
     } catch (error) {
       console.error('删除消息失败:', error);
       Alert.alert('删除失败', '无法删除消息');
@@ -1224,7 +1221,7 @@ export const useChatScreen = () => {
       setLastSeq(0);
       setFirstSeq(0);
       setHasMoreHistory(true);
-      await clearConversationMessages(conversationId);
+      await messageRepository.clearConversation(conversationId);
       // 刷新消息列表
       await refreshMessages();
     } catch (error) {