feat: add mui

src/client/App.tsx

@@ -1,5 +1,7 @@
+import Button from '@mui/material/Button';
+
 function App() {
-  return <div>the app.</div>
+  return <div>the app: <Button variant='contained'>Click here</Button></div>
 }
 
 export default App;

src/client/main.tsx

@@ -1,3 +1,8 @@
+import '@fontsource/roboto/300.css';
+import '@fontsource/roboto/400.css';
+import '@fontsource/roboto/500.css';
+import '@fontsource/roboto/700.css';
+
 import React from "react";
 import ReactDOM from "react-dom/client";