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/components/common/ImageGallery.tsx

@@ -14,6 +14,7 @@ import {
   Text,
   StatusBar,
   Alert,
+  Platform,
 } from 'react-native';
 import { Image as ExpoImage } from 'expo-image';
 import {
@@ -126,6 +127,10 @@ export const ImageGallery: React.FC<ImageGalleryProps> = ({
   // 打开/关闭时重置状态
   useEffect(() => {
     if (visible) {
+      if (Platform.OS === 'web') {
+        const active = (globalThis as any)?.document?.activeElement as { blur?: () => void } | undefined;
+        active?.blur?.();
+      }
       setCurrentIndex(initialIndex);
       setShowControls(true);
       setError(false);