cut-release

Cut a release end-to-end — promote CHANGELOG [Unreleased] into a dated version block (auto-drafting any gap entries via /changelog), open the prepare-release PR, watch for its merge, then push the vX.Y.Z tag that triggers the release pipeline. The human's one checkpoint is reviewing/merging the changelog PR; the tag fires automatically once it merges. Triggers on "cut a release" / "cut vX.Y.Z".