Docker support for one-command setup

[MeisnerDan]

Create a Dockerfile and docker-compose.yml that allows users to run Mission Control with a single command. This dramatically lowers the barrier to entry for non-technical users and ensures consistent environments across machines. The Docker image should include Node.js, pnpm, and all dependencies pre-installed.

Acceptance Criteria

• Dockerfile builds a production-ready Next.js image
• docker-compose.yml includes necessary services (if any) and port mappings
• Running docker-compose up starts Mission Control on localhost:3000
• Data persistence: task data stored in a Docker volume so it survives container restarts
• Development mode: separate docker-compose.dev.yml for local development with hot reload
• .dockerignore excludes unnecessary files (node_modules, .git, etc.)
• README includes Docker setup instructions and troubleshooting
• GitHub Actions CI builds and publishes Docker image on releases
• Docker image size optimized (use multi-stage builds)