Docker multi-stage build optimization

Optimize Docker images using multi-stage builds. Techniques: 1. Separate build and runtime stages. 2. Use slim base images (alpine, distroless). 3. Leverage layer caching with proper ordering. 4. Copy only necessary artifacts to final stage. 5. Use .dockerignore to exclude files. 6. Run as non-root user for security. 7. Scan for vulnerabilities with Trivy. Example for Node.js app: reduce image from 1GB to 150MB. Include CI integration and registry best practices.