fix: resize images in a separate isolate

lib/utils/run_in_background.dart

@@ -0,0 +1,12 @@
+import 'package:isolate/isolate.dart';
+import 'dart:async';
+
+Future<T> runInBackground<T, U>(
+    FutureOr<T> Function(U arg) function, U arg) async {
+  final isolate = await IsolateRunner.spawn();
+  try {
+    return await isolate.run(function, arg);
+  } finally {
+    await isolate.close();
+  }
+}