Add deploy_server Drone pipeline that builds and pushes the Docker image
to Gitea Container Registry, then deploys to VPS via SSH. Switch
Dockerfile from git clone to COPY-based build for CI compatibility and
better layer caching. Change exposed port to 3001.
- Add multi-stage Dockerfile for server containerization
- Add .dockerignore to exclude unnecessary files from build context
- Switch shared package from source to compiled CommonJS output (dist/)
- Server dev/build scripts now build shared package first
- Fix deep imports to use @calchat/shared barrel export
- Update CLAUDE.md with Docker and shared package documentation
