feat(qr-server): migrate to uv with PEP 723 inline dependencies

- Replace requirements.txt with inline script dependencies in server.py
- Add package.json with npm scripts for run-all.ts integration
- Update CI workflow to install uv via astral-sh/setup-uv@v5
- Update Docker commands to install uv for e2e tests
- Add Playwright golden screenshot for qr-server
- Update README with uv installation and usage instructions

examples/qr-server/widget.html

@@ -27,7 +27,7 @@
 <body>
   <div id="qr"></div>
   <script type="module">
-    import { App } from "https://unpkg.com/@modelcontextprotocol/ext-apps@0.3.1/app-with-deps";
+    import { App } from "https://unpkg.com/@modelcontextprotocol/ext-apps@0.4.0/app-with-deps";
 
     const app = new App({ name: "QR Widget", version: "1.0.0" });