Gitea's auto GITHUB_TOKEN lacks the package scope needed to push to the container registry, causing the login step to fail. Switch the login password to a PAT stored as the REGISTRY_TOKEN repo Actions secret (scopes: write:package, read:package).
Adds .gitea/workflows/release.yml. On a v* git tag push (or manual dispatch), builds the Dockerfile and publishes to git.linuxhg.com/bookhoard/bookhoard under two tags: the version (${{ gitea.ref_name }}) and 'latest'. Auth uses the auto-provided GITHUB_TOKEN; no secret to manage. Pushes to main do nothing, so work-in-progress commits never ship.
john-okeefe