feat(ui): implement keyword highlighting and improve search experience

- Add keyword highlighting in `PostCard` and `PostContentRenderer` using `HighlightText`.
- Implement smart excerpt logic in `PostCard` to show relevant context around search keywords.
- Update `SearchBar` styles for better visual feedback and consistency.
- Enhance `SearchScreen` with modern tab variants and improved tag styling.
- Add support for updating group descriptions in `GroupInfoScreen` and `GroupService`.
- Refactor various UI components for improved layout stability and typography.

src/screens/profile/UserProfileScreen.tsx

@@ -104,7 +104,7 @@ export const UserProfileScreen: React.FC<UserProfileScreenProps> = ({ mode, user
       <EmptyState
         title={emptyTitle}
         description={emptyDesc}
-        icon={activeTab === 0 ? 'file-document-edit-outline' : 'bookmark-heart-outline'}
+        icon={activeTab === 0 ? 'file-document-edit-outline' : 'bookmark-outline'}
         variant="modern"
       />
     );