Mirrors the working mediaDrop pipeline (.forgejo/workflows/publish-docker.yml
there) on the same instance: push to master -> latest + short-sha tags,
push a vX.Y.Z tag -> X.Y.Z/X.Y/latest. REGISTRY_TOKEN secret already
present on this repo. No test job yet - nothing to test.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
