Dockerfile Best Practices Generator

## Overview This crystal produces a Dockerfile that follows Docker's official best practices: multi-stage builds to minimize final image size, layer cache optimization to speed up rebuild times, and security hardening to reduce the attack surface of your container images. ## Supported Runtimes - **Node.js** — Alpine-based final stage with non-root user, `.npmrc` secrets mounted at build time - **Python** — slim base image with pip cache and virtual environment isolation - **Go** — distroless or scratch final image for sub-20 MB production binaries - **Java** — Eclipse Temurin base with jlink custom JRE for minimal footprint