- use workflow_run.repository.full_name for gh API queries
- expose GITHUB_TOKEN as GH_TOKEN for the GitHub CLI
- improve log messages and keep tag skipped when checks are missing or failing
- add mark-stable workflow that runs on workflow_run for all test pipelines
- use GitHub API to ensure all required workflows succeeded before moving the 'stable' tag
- add Nix flake.lock to pin nixpkgs for reproducible builds
https://chatgpt.com/share/693aa4a6-7460-800f-ba47-cfc15b1b2236