Code-review polish on admin_coverage_test.go:
- Replace inline artist-seed SQL with the seedArtist helper used
across the rest of the api test suite (admin_covers_test.go,
likes_test.go, me_history_test.go, admin_quarantine_test.go).
- Rename the cover_art_source pointer locals from none/sidecar/mbcaa
to sourceNone/sourceSidecar/sourceMbcaa so they don't read like
zero-value identifiers.
New admin handler returns the library-wide cover-art coverage rollup
{total, with_art, pending, settled, pending_no_mbid} for the admin
dashboard gauge. Always 200; zeros on empty library. Same RequireAdmin
middleware as /api/admin/scan/status. Lives under a new /library/
admin sub-namespace, parallel to /scan/ (per-run state) and /covers/
(actions).
Tests gated on MINSTREL_TEST_DATABASE_URL: empty library returns all
zeros, mixed rows produce correct bucket math (verifying the
with_art + pending + settled = total invariant), non-admin returns 403.
bvandeusen