Add re-usable base home page

mobile/packages/ui/lib/pages/base_home_page.dart

@@ -0,0 +1,7 @@
+import 'package:flutter/material.dart';
+
+abstract class BaseHomePage extends StatefulWidget {
+  const BaseHomePage({super.key});
+}
+
+abstract class BaseHomePageState<T extends BaseHomePage> extends State<T> {}