On push to main (and v* tags), builds the Docker image and pushes it to
the Forgejo container registry at git.plexultra.com/dlawler489/printhive
(:latest and :<short-sha>). Uses the auto-provided Actions token with
packages:write; plain docker CLI so it only needs the checkout action.
Compose image reference updated to the Forgejo registry.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
