- Added `Sidebar` component with responsive layout for chat navigation.
- Implemented `ChatStore` for managing chat data and fetching user chats.
- Integrated JSON:API `ChatCollection` for consistent backend responses.
- Added `GetUserChatsAction` to retrieve paginated user chats.
- Refactored frontend to separate `ChatStore` and `MessageStore` for improved state management.
- Updated styles, components, and tests for seamless chat interactions.