Runner fetches the composite action from @main; main still had
upload-artifact@v4 which fails on Gitea (GHESNotSupportedError).
Brings the v3 action.yml from feature/python-rewrite-and-linux-migration.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Required so `uses: .../local-ci-build@main` resolves: the action only
existed on feature/python-rewrite-and-linux-migration. Brings just the
action.yml (host-side orchestrator unchanged) without merging the full
migration branch.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Simone