Code-review polish on GetAlbumCoverageRollup's comment block:
- Records the invariant that with_art + pending + settled = total
(and that pending_no_mbid is a subset of pending, not a fourth
bucket).
- Notes that the IN ('sidecar','embedded','mbcaa') list must stay
in sync with the cover_art_source CHECK constraint in migration
0016 — without this note a future source addition could silently
undercount with_art.
bvandeusen
ff5868bdab