Fix MSAL popup loading full app — skip React render when in popup context

MSAL parent polls popup URL for auth code (same-origin), so the popup
doesn't need to render anything. Prevents app from opening inside popup.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/main.tsx

@@ -2,4 +2,9 @@ import { createRoot } from 'react-dom/client'
 import App from './App.tsx'
 import './index.css'
 
-createRoot(document.getElementById("root")!).render(<App />);
+// If loaded inside an MSAL popup, don't render the app.
+// The parent window's MSAL instance polls the popup URL for the auth code
+// and processes it — no React needed here.
+if (window.opener === null || window.opener === window) {
+  createRoot(document.getElementById("root")!).render(<App />);
+}