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/profile/SettingsScreen.tsx

@@ -62,7 +62,6 @@ const SETTINGS_GROUPS_BASE = [
     icon: 'bell-outline',
     items: [
       { key: 'notification_settings', title: '通知设置', icon: 'bell-cog-outline', showArrow: true, subtitle: '推送、震动、提示音' },
-      { key: 'language', title: '语言设置', icon: 'translate', showArrow: true, subtitle: '简体中文' },
       { key: 'data_storage', title: '数据与存储', icon: 'database-outline', showArrow: true },
     ],
   },
@@ -72,8 +71,6 @@ const SETTINGS_GROUPS_BASE = [
     items: [
       { key: 'about', title: '关于我们', icon: 'information-outline', showArrow: true, subtitle: `版本 ${APP_VERSION}` },
       { key: 'help', title: '帮助与反馈', icon: 'help-circle-outline', showArrow: true },
-      { key: 'terms', title: '用户协议', icon: 'file-document-outline', showArrow: true },
-      { key: 'privacy_policy', title: '隐私政策', icon: 'shield-outline', showArrow: true },
     ],
   },
 ];
@@ -240,31 +237,18 @@ export const SettingsScreen: React.FC = () => {
         );
         break;
       }
-      case 'language': {
-        Alert.alert(
-          '语言设置',
-          '选择应用显示语言',
-          [
-            { text: '取消', style: 'cancel' },
-            { text: '简体中文', onPress: () => {} },
-            { text: '繁體中文', onPress: () => {} },
-            { text: 'English', onPress: () => {} },
-          ]
-        );
-        break;
-      }
+
       case 'data_storage': {
         Alert.alert('数据与存储', '缓存清理功能即将上线！');
         break;
       }
-      case 'terms': {
-        Alert.alert('用户协议', '用户协议页面即将上线！');
+      case 'about':
+        router.push(hrefs.hrefProfileAbout());
         break;
-      }
-      case 'privacy_policy': {
-        Alert.alert('隐私政策', '隐私政策页面即将上线！');
+      case 'help':
+        Alert.alert('帮助与反馈', '帮助中心即将上线！');
         break;
-      }
+
       case 'edit_profile':
         router.push(hrefs.hrefProfileEdit());
         break;
@@ -372,7 +356,7 @@ export const SettingsScreen: React.FC = () => {
           萝卜社区 v{APP_VERSION}
         </Text>
         <Text variant="caption" color={colors.text.hint} style={styles.copyright}>
-          © 2024 Carrot BBS. All rights reserved.
+          © 2026 青春之旅电子信息科技（威海）有限公司
         </Text>
       </View>
     </>