Add the step-by-step fixer and library types

Each pair is a Music (Artist/Album/01 Title) or Soundtracks (Album/01 Title)
library. The new Fixer tab takes the master, then the slave, through four
reviewed steps: folder structure, album tags (optional MusicBrainz lookup;
the slave reuses the fixed master's tags), folder names and file names,
then links the two libraries. Every fix is an undoable operation.

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

internal/store/store.go

@@ -132,6 +132,10 @@ var migrations = []string{
 
 	// 9: Lidarr-style naming (artist/album folder and track formats) as JSON.
 	`ALTER TABLE pairs ADD COLUMN organize_config TEXT NOT NULL DEFAULT '';`,
+
+	// 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 '';`,
 }
 
 // SchemaVersion is the newest database schema this build knows.