After a stable release, main stayed inside the old pre-mode cycle, so the next
beta numbered below the published stable (v0.73.0-beta.7 after v0.73.0) and the
dev checkout kept reporting the last beta.
- beta releases re-anchor a stale pre-mode cycle on the newest stable tag
- both channels refuse a version at or below the newest published stable
- stable promotion now back-merges release into main automatically (fail-soft
on conflict) so the local dev version is the stable version