Adds AppLoadingIndicator widget and replaces CircularProgressIndicator in SceneView.

lib/features/shared_widgets/app_loading_indicator.dart

@@ -0,0 +1,12 @@
+import 'package:flutter/material.dart';
+
+class AppLoadingIndicator extends StatelessWidget {
+  const AppLoadingIndicator({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: CircularProgressIndicator.adaptive(),
+    );
+  }
+}