fix: create router per mount for test isolation

Move createHashRouter() from module level into a createRouter() factory
called in the class constructor. Each Index mount gets a fresh router
instance, preventing stale location state from leaking between
integration tests.

Co-authored-by: Francis Nepomuceno <n3ps@users.noreply.github.com>

Author: cursoragent

ui/pages/index.js

@@ -57,21 +57,25 @@ function AppProviders() {
   );
 }
 
-const router = createHashRouter([
-  {
-    element: <AppProviders />,
-    children: [
-      {
-        element: <Routes />,
-        children: routeConfig,
-      },
-    ],
-  },
-]);
+function createRouter() {
+  return createHashRouter([
+    {
+      element: <AppProviders />,
+      children: [
+        {
+          element: <Routes />,
+          children: routeConfig,
+        },
+      ],
+    },
+  ]);
+}
 
 class Index extends PureComponent {
   state = {};
 
+  router = createRouter();
+
   static getDerivedStateFromError(error) {
     return { error };
   }
@@ -102,7 +106,7 @@ class Index extends PureComponent {
 
     return (
       <Provider store={store}>
-        <RouterProvider router={router} />
+        <RouterProvider router={this.router} />
       </Provider>
     );
   }