tools/sync_github_metadata.py holds the 221 lines that were embedded in
sync-github-metadata.yml, unchanged in behaviour and messages. The scoped
workflow now checks out TirSystem/github-action at main and runs the file
(33 lines instead of 230). The tests import the file instead of executing
the YAML. Verified live from TirSystem-BashScript/RepoFoundry with that
organisation's secrets.
Task: MIL-004#6
