feat: refactor sgclaw around zeroclaw compat runtime

third_party/zeroclaw/web/src/main.tsx

@@ -0,0 +1,15 @@
+import React from 'react';
+import ReactDOM from 'react-dom/client';
+import { BrowserRouter } from 'react-router-dom';
+import App from './App';
+import { basePath } from './lib/basePath';
+import './index.css';
+
+ReactDOM.createRoot(document.getElementById('root')!).render(
+  <React.StrictMode>
+    {/* basePath is injected by the Rust gateway at serve time for reverse-proxy prefix support. */}
+    <BrowserRouter basename={basePath || '/'}>
+      <App />
+    </BrowserRouter>
+  </React.StrictMode>
+);