fix: post-merge type and test fixes

Library.vue: use Song type from store so SongCard's strict platform
union accepts the data (was platform: string, broke after merge tightened
SongCard prop type).

database.test.ts: switch toEqual -> toMatchObject so getBotInstances()
returning extra profile_* schema columns no longer fails the assertion.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/data/database.test.ts

@@ -68,7 +68,7 @@ describe("database", () => {
     botDb.saveBotInstance(instance);
     const instances = botDb.getBotInstances();
     expect(instances).toHaveLength(1);
-    expect(instances[0]).toEqual(instance);
+    expect(instances[0]).toMatchObject(instance);
     expect(instances[0].autoStart).toBe(true);
 
     // Test upsert