- Add .gitea/workflows/release.yml for Gitea builds
- Uses plain docker commands (no action dependencies)
- Pushes to git.prettyhefty.com registry
- Simplify .github/workflows/build.yaml for GitHub only
- Remove Gitea detection logic
- Only push latest tag for non-prerelease versions
The workflow was checking vars.GITEA_ACTIONS (repository variable)
but Gitea sets GITEA_ACTIONS as an environment variable. This caused
Gitea builds to incorrectly try using ghcr.io.