Stamping '## Unreleased' away left main with no heading for a PR
authored before the release to land in, so its entry merged cleanly
into the section that just shipped. The ceremony now re-arms, and
changelog-armed.sh enforces it keyed on VERSION -- so the ceremony
PR's own bare-VERSION tree stays legal (rig#44 / cast#108).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
