fix: run sqlite on background isolate

lib/database/app_database.dart

@@ -225,7 +225,7 @@ LazyDatabase _openConnection() {
       }
     }
 
-    return NativeDatabase(file, setup: (db) {
+    return NativeDatabase.createInBackground(file, setup: (db) {
       db.execute('PRAGMA journal_mode=WAL');
       db.execute('PRAGMA synchronous=NORMAL');
     });