- Add workflow-level concurrency to avoid overlapping releases
- Enable BuildKit cache (GHA) for faster Docker builds
- Simplify to a single multi-arch build (linux/amd64, linux/arm64)
- Remove digest export/upload and manifest merge steps
- Push manifest directly from buildx with tag `latest`
- Fix GitHub Release token casing to use `secrets.GITHUB_TOKEN`
- Update Dockerfile to use TARGETARCH for correct package selection
- Pass VERSION consistently; write version to image
No functional change to runtime behavior expected; improves speed, reliability, and maintainability of the release pipeline.