Refactor VPN proxy client implementation

src/web/main.tsx

@@ -0,0 +1,8 @@
+import { createRoot } from 'react-dom/client';
+
+import { App } from './App.js';
+import './styles/index.css';
+
+const root = document.getElementById('root');
+if (!root) throw new Error('Harbor root element not found');
+createRoot(root).render(<App />);