docs: add MCP client configuration to example READMEs

Add stdio transport configuration snippets near the top of each example
README to help users quickly set up the servers in their MCP clients.

- Node.js examples use npx with the published npm packages
- Python qr-server uses uv with local path
- Removed Claude Desktop-specific references from qr-server

examples/threejs-server/README.md

@@ -4,6 +4,27 @@
 
 Interactive 3D scene renderer using Three.js. Demonstrates streaming code preview and full MCP App integration.
 
+## MCP Client Configuration
+
+Add to your MCP client configuration (stdio transport):
+
+```json
+{
+  "mcpServers": {
+    "threejs": {
+      "command": "npx",
+      "args": [
+        "-y",
+        "--silent",
+        "--registry=https://registry.npmjs.org/",
+        "@modelcontextprotocol/server-threejs",
+        "--stdio"
+      ]
+    }
+  }
+}
+```
+
 ## Features
 
 - **Interactive 3D Rendering**: Execute JavaScript code to create and animate Three.js scenes