Add ability to search messages within a specific conversation. This includes:
- New `MessageSearchScreen` for displaying search results.
- `MessageRepository.searchByConversation` to query messages by keyword and conversation ID.
- Integration of search entry points in `GroupInfoScreen` and `PrivateChatInfoScreen`.
- Support for scrolling to a specific message sequence (`scrollToSeq`) when navigating from search results.
- Enhanced `HighlightText` component to support custom highlight styles.
feat(message): implement message search functionality
- Updated App entry point to utilize Expo Router, simplifying the navigation setup.
- Removed legacy navigation components and services to streamline the codebase.
- Adjusted package.json to reflect the new entry point and updated dependencies for compatibility.
- Enhanced overall application structure by consolidating navigation logic and improving maintainability.