Add cookie-banner React example app

Interactive playground with themed banner, headless components,
and debug tabs demonstrating programmatic consent access via
getConsent() across separate bundles.

Signed-off-by: Émile Ré <emile@probo.com>

examples/cookie-banner-react/src/main.tsx

@@ -0,0 +1,7 @@
+import { StrictMode } from "react";
+import { createRoot } from "react-dom/client";
+import { App } from "./App";
+
+createRoot(document.getElementById("root")!).render(
+  <App />
+);