Revert "Flag slave-only songs whose album or artist the master has"

This reverts commit 4bae674.

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

internal/store/store.go

@@ -140,9 +140,6 @@ var migrations = []string{
 	// 10: library type (music or soundtracks) and the step-by-step fixer's progress.
 	`ALTER TABLE pairs ADD COLUMN library_type TEXT NOT NULL DEFAULT 'music';
 	ALTER TABLE pairs ADD COLUMN fixer_state TEXT NOT NULL DEFAULT '';`,
-
-	// 11: slave-only songs whose album or artist the master has.
-	`ALTER TABLE matches ADD COLUMN missing TEXT NOT NULL DEFAULT '';`,
 }
 
 // SchemaVersion is the newest database schema this build knows.