Forgejo's local Actions-artifact storage defaults to
/var/lib/forgejo/data/actions_artifacts but Forgejo does not pre-create it.
The artifact endpoint ingests the chunked upload, then the merge-chunks step
fails with 'lstat .../actions_artifacts/tmpNNN: no such file or directory',
so every upload-artifact step dies after a successful build. Pre-create the
dir (forgejo-owned) via tmpfiles. actions.ENABLED already registers the
endpoints; this gives them somewhere to write.
bfeb23ce06