feat(db/m7-cover-sources): SQL queries for provider settings + recheck

- Extends GetAlbumCoverageRollup's with_art FILTER to include
  'theaudiodb' so F's coverage gauge surfaces TheAudioDB-found rows
  as with_art rather than silently undercounting.
- Modifies ListAlbumsMissingCover to take the current sources_version
  as a parameter; eligibility now includes stale-'none' rows.
- Adds SetAlbumCoverWithVersion (atomic write of path + source +
  version stamp) and the parallel SetArtistArtWithVersion +
  ClearArtistArtNone + ListArtistsMissingArt for the artist-art
  enricher.
- New coverart_settings.sql with ListProviderSettings,
  UpsertProviderSettings (boot reconciliation, preserves operator
  values on conflict), UpdateProviderSettings (admin PATCH; tri-
  state api_key handling), GetCurrentSourcesVersion,
  BumpSourcesVersion (RETURNING the new value).

internal/db/dbq/covers.sql.go

@@ -109,41 +109,38 @@ func (q *Queries) GetAlbumWithFirstTrackPath(ctx context.Context, id pgtype.UUID
 
 const listAlbumsMissingCover = `-- name: ListAlbumsMissingCover :many
 
-SELECT a.id, a.mbid, a.title, a.artist_id
+SELECT a.id
   FROM albums a
  WHERE a.cover_art_source IS NULL
- ORDER BY a.created_at ASC
- LIMIT $1
+    OR (a.cover_art_source = 'none' AND a.cover_art_sources_version != $1)
+ ORDER BY a.created_at
+ LIMIT $2
 `
 
-type ListAlbumsMissingCoverRow struct {
-	ID       pgtype.UUID
-	Mbid     *string
-	Title    string
-	ArtistID pgtype.UUID
+type ListAlbumsMissingCoverParams struct {
+	CoverArtSourcesVersion int32
+	Limit                  int32
 }
 
 // M7 #353: album cover enrichment queries.
-// Albums where cover_art_source has never been set. Used by the boot
-// backfill and post-scan enrichment passes. LIMIT supplied by caller.
-func (q *Queries) ListAlbumsMissingCover(ctx context.Context, limit int32) ([]ListAlbumsMissingCoverRow, error) {
-	rows, err := q.db.Query(ctx, listAlbumsMissingCover, limit)
+// M7 cover-sources: returns rows the enricher should attempt. Eligible:
+// cover_art_source IS NULL (never tried), OR cover_art_source = 'none'
+// AND cover_art_sources_version != current (settled under an older
+// source set; recheck against the current chain). LIMIT supplied by
+// caller for batching.
+func (q *Queries) ListAlbumsMissingCover(ctx context.Context, arg ListAlbumsMissingCoverParams) ([]pgtype.UUID, error) {
+	rows, err := q.db.Query(ctx, listAlbumsMissingCover, arg.CoverArtSourcesVersion, arg.Limit)
 	if err != nil {
 		return nil, err
 	}
 	defer rows.Close()
-	var items []ListAlbumsMissingCoverRow
+	var items []pgtype.UUID
 	for rows.Next() {
-		var i ListAlbumsMissingCoverRow
-		if err := rows.Scan(
-			&i.ID,
-			&i.Mbid,
-			&i.Title,
-			&i.ArtistID,
-		); err != nil {
+		var id pgtype.UUID
+		if err := rows.Scan(&id); err != nil {
 			return nil, err
 		}
-		items = append(items, i)
+		items = append(items, id)
 	}
 	if err := rows.Err(); err != nil {
 		return nil, err