library: stop artist art updates from reindexing artist search

The materialized art update rewrote every artist row on every library-changing sync. That fired the FTS5 content-sync triggers for each artist, which was the real cost: the same SQL is ~10ms with the triggers removed and ~4.7s for 100 changed artists with them in place. Only update rows whose cover lists actually changed, and replace the generated artist search triggers with UPDATE OF name, sortName so art-only writes never touch the FTS index. Existing databases get this through migration 36->37; fresh databases get it from the onCreate callback.

app/src/main/kotlin/com/subtracks/data/db/DbLogging.kt

@@ -114,6 +114,12 @@ class LoggedMigration(
     }
 }
 
+internal object ArtistSearchTriggerOptimization : RoomDatabase.Callback() {
+    override suspend fun onCreate(connection: SQLiteConnection) {
+        optimizeArtistSearchTriggers(connection)
+    }
+}
+
 internal object SqliteLifecycleLogging : RoomDatabase.Callback() {
     override suspend fun onCreate(connection: SQLiteConnection) {
         Log.i("sql", "created fresh database")