The step was gated on github.event_name == 'release'. v3.8.50's package shipped
through a workflow_dispatch (the staged publish, 11 attempts) and the step was
skipped, so the GitHub Release carried no SBOM — it was attached by hand from the
run's sbom-npm artifact (5.0 MB, 1,886 components). Now it attaches on release or
workflow_dispatch whenever a release for the published tag exists, and says so
when it does not (the workflow artifact remains the durable copy either way).
actionlint and prettier clean; npm-publish-artifact-provenance and
check-workflows-provenance-runner suites pass.