feat: Add Docker support for Onebox deployment with multi-stage Docke…

…rfile and supervisord configuration

- Introduce docker-compose.yml to define services for the Onebox deployment, including backend and frontend configurations.
- Create a multi-stage Dockerfile to build and run a combined Next.js frontend and FastAPI backend in a single image.
- Add supervisord configuration to manage both frontend and backend processes within the container.
- Update frontend configuration to handle API requests through rewrites for seamless integration with the backend.