fix: clearing a wrong slot's MBID clears its source too, as tracks_mbid_source_pair requires (M498)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/db/dbq/tracks.sql.go

@@ -58,7 +58,7 @@ func (q *Queries) ClearStaleSuspectSourceTracks(ctx context.Context, pattern str
 
 const clearTrackMbids = `-- name: ClearTrackMbids :exec
 UPDATE tracks
-   SET mbid = NULL
+   SET mbid = NULL, mbid_source = NULL
  WHERE id = ANY($1::uuid[])
 `
 
@@ -66,6 +66,7 @@ UPDATE tracks
 // wrong-slot removal). The MBID came from that file, so it names the song kept
 // elsewhere on the album, and missing-pair folding would fold the emptied slot
 // into it: twelve slots went that way on 2026-10-20 and were never wanted back.
+// mbid_source goes with it (tracks_mbid_source_pair).
 func (q *Queries) ClearTrackMbids(ctx context.Context, ids []pgtype.UUID) error {
 	_, err := q.db.Exec(ctx, clearTrackMbids, ids)
 	return err

internal/db/queries/tracks.sql

@@ -221,8 +221,9 @@ UPDATE tracks
 -- wrong-slot removal). The MBID came from that file, so it names the song kept
 -- elsewhere on the album, and missing-pair folding would fold the emptied slot
 -- into it: twelve slots went that way on 2026-10-20 and were never wanted back.
+-- mbid_source goes with it (tracks_mbid_source_pair).
 UPDATE tracks
-   SET mbid = NULL
+   SET mbid = NULL, mbid_source = NULL
  WHERE id = ANY(sqlc.arg(ids)::uuid[]);
 
 -- name: ClearTracksMissing :execrows

internal/library/duplicate_resolve_test.go

@@ -383,7 +383,7 @@ func TestResolveDuplicates_RemovesACopyFromAnotherSongsSlot_Integration(t *testi
 	seedTrackList(t, f.pool, f.album, map[string]int{"Void": 220500, "Reach": 281000})
 	// The wrong file is Void's recording, so it carries Void's MBID.
 	if _, err := f.pool.Exec(context.Background(),
-		`UPDATE tracks SET mbid = 'rec-void' WHERE id = ANY($1)`, []pgtype.UUID{f.a.ID, f.b.ID}); err != nil {
+		`UPDATE tracks SET mbid = 'rec-void', mbid_source = 'tag' WHERE id = ANY($1)`, []pgtype.UUID{f.a.ID, f.b.ID}); err != nil {
 		t.Fatal(err)
 	}
 	res, err := ResolveDuplicates(context.Background(), f.pool, nil, "", true)