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/GroupInfoScreen.tsx

@@ -118,6 +118,13 @@ const GroupInfoScreen: React.FC = () => {
   const [inviteModalVisible, setInviteModalVisible] = useState(false);
   const [inviting, setInviting] = useState(false);
 
+  useEffect(() => {
+    if ((editModalVisible || announcementModalVisible || transferModalVisible || joinTypeModalVisible || inviteModalVisible) && Platform.OS === 'web') {
+      const active = (globalThis as any)?.document?.activeElement as { blur?: () => void } | undefined;
+      active?.blur?.();
+    }
+  }, [editModalVisible, announcementModalVisible, transferModalVisible, joinTypeModalVisible, inviteModalVisible]);
+
   // 计算当前用户的角色
   const isOwner = currentMember?.role === 'owner';
   const isAdmin = currentMember?.role === 'admin' || isOwner;