Update Vite configuration to use base path from environment and simplify proxy settings; adjust main entry point for BrowserRouter basename.

frontend/src/main.jsx

@@ -1,14 +1,13 @@
-import { StrictMode } from "react";
-import { createRoot } from "react-dom/client";
-import { BrowserRouter } from "react-router-dom";
+import { StrictMode } from 'react'
+import { createRoot } from 'react-dom/client'
+import { BrowserRouter } from 'react-router-dom'
+import App from './App.jsx'
+import './index.css'
 
-import "./index.css";
-import App from "./App.jsx";
-
-createRoot(document.getElementById("root")).render(
+createRoot(document.getElementById('root')).render(
   <StrictMode>
-    <BrowserRouter>
+    <BrowserRouter basename={import.meta.env.BASE_URL}>
       <App />
     </BrowserRouter>
-  </StrictMode>,
-);
+  </StrictMode>
+)