A multi-stage build leaves untagged <none> intermediate layers behind that pile
up across rebuilds. After the build (and the dist export, which still needs the
final image), run `docker image prune -f` to drop them. Only DANGLING images are
removed — the final image, the pulled CUDA base, and any other tagged images are
kept. Default on; disable with --no-prune.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>