Stamp the ceremony: VERSION 0.7.1-dev -> 0.8.0 (bare), and rewrite
'## Unreleased' into '## 0.8.0 — 2026-07-19' with an empty '## Unreleased'
put back above it — the re-arm half of the two-edit stamp (#108), so main is
never disarmed between this merge and the automatic -dev bump.
0.8.0 rather than 0.7.1: the section carries an '### Added' (#96, the merge
door), and #105 changes 'box restore' to ask before it destroys — which
breaks non-interactive callers that did not pass --force.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
