Spec: docs/superpowers/specs/2026-05-13-note-version-pinning-design.md
- pin_kind: NULL=rolling, 'auto'=stability-scan, 'manual'=user-declared.
- pin_label: NULL for rolling; auto-generated for 'auto'; user-supplied
string for 'manual' (may be NULL).
No backfill — every existing row stays rolling. The daily auto-pin scan
will catch up on the first run after deploy.
