feat: complete docker containerization and cantine application setup
- Transform voting app to cantine (canteen) management system
- Add complete PostgreSQL schema with products, ingredients, BOM, production orders
- Implement multi-stage Dockerfiles for frontend and backend
- Configure docker-compose with environment variables externalization
- Add health check API endpoint for production monitoring
- Setup proper .dockerignore files to optimize build context
- Configure Next.js standalone output for optimal container size
- Add comprehensive documentation and project roadmap