feat: scaffold frontend app structure

frontend/src/main.tsx

@@ -0,0 +1,12 @@
+import React from "react";
+import ReactDOM from "react-dom/client";
+import { RouterProvider } from "react-router-dom";
+import { appRouter } from "./app/router";
+import "./styles/tokens.css";
+import "./styles/global.css";
+
+ReactDOM.createRoot(document.getElementById("root") as HTMLElement).render(
+  <React.StrictMode>
+    <RouterProvider router={appRouter} />
+  </React.StrictMode>
+);