1ab9bc70d1
GitHub release immutability locks a release's assets at publish time. The current flow publishes the release in github-release and only afterwards uploads the Sigstore provenance bundle (P21.1e) via 'gh release upload', which immutability would reject (actions/attest-build-provenance#734). Reorder to draft -> attach everything -> publish: - github-release now creates the release as a draft (draft: true) with all build artefacts. - attestations attaches the provenance bundle to the draft (gh release upload works on drafts), unchanged otherwise. - a new publish-release job flips the draft to published + latest, gated on 'always() && needs.github-release.result == success' so a Sigstore hiccup in attestations costs only the provenance asset, never the release — the same isolation as before. A skipped github-release (failed publish) skips this too. Correct with immutability off (today: release ends published with every asset) and on (later, user toggle: all assets present before the lock). No behaviour removed; nothing deleted.