fix(qr-server): Update SDK to 0.3.1 with app-with-deps bundle

- Use app-with-deps export for CDN imports (includes all dependencies)
- Fixes widget crash on Claude Desktop/Nest

examples/qr-server/widget.html

@@ -27,7 +27,7 @@
 <body>
   <div id="qr"></div>
   <script type="module">
-    import { App, PostMessageTransport } from "https://unpkg.com/@modelcontextprotocol/ext-apps@0.0.1";
+    import { App } from "https://unpkg.com/@modelcontextprotocol/ext-apps@0.3.1/app-with-deps";
 
     const app = new App({ name: "QR Widget", version: "1.0.0" });