Add kanji page

lib/screens/misc/loading.dart

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