This pull request introduces real-time remote cursor support to the collaborative board, improves WebSocket integration, and adds backend and frontend infrastructure for better development and testing. The most significant changes are the addition of remote cursor visualization, a new custom React hook for WebSocket board communication, and backend updates to support these features. It also adds Docker support and basic API tests.

Frontend: Real-time Collaboration Features

• Added a RemoteCursorsOverlay React component to visually display other users' cursors on the board, showing their position and username. (apps/frontend/src/components/board/RemoteCursorsOverlay.tsx apps/frontend/src/components/board/RemoteCursorsOverlay.tsxR1-R69)
• Implemented the useBoardWebSocket custom hook to manage WebSocket connections, handle incoming cursor and document update events, and maintain a list of remote user cursors. (apps/frontend/src/hooks/useBoardWebSocket.ts apps/frontend/src/hooks/useBoardWebSocket.tsR1-R123)
• Integrated remote cursor sending and display into the BoardPage, wiring up pointer movement to broadcast the current user's cursor and rendering the overlay for remote cursors. (apps/frontend/src/pages/board/BoardPage.tsx [1] [2] [3]

Frontend: WebSocket Utilities

• Added utility functions getWsBaseUrl and getBoardWsUrl to construct proper WebSocket URLs for board communication, supporting both HTTP and HTTPS environments. (apps/frontend/src/lib/api.ts apps/frontend/src/lib/api.tsR24-R38)

Backend: WebSocket and API Enhancements

• Updated the backend WebSocket router to include user_id and username in cursor.moved events, enabling the frontend to identify and label remote cursors. (api/app/app/websocket/router.py api/app/app/websocket/router.pyL56-R61)

Development and Testing Infrastructure

• Added a .dockerignore file and a new Dockerfile for the API, using Python 3.12 and uv for dependency management, to facilitate containerized development and deployment. (api/app/.dockerignore [1] api/app/Dockerfile [2]
• Introduced basic API test infrastructure with pytest configuration, fixtures, and initial tests for authentication and health endpoints. (api/app/pyproject.toml [1] [2] api/app/tests/conftest.py [3] api/app/tests/test_api_auth.py [4] api/app/tests/test_health.py [5]