docs: note Bun requirement in README examples section

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Co-Authored-By: Claude <[email protected]>

Author: ochafik

README.md

@@ -55,7 +55,8 @@ The [`examples/`](https://github.com/modelcontextprotocol/ext-apps/tree/main/exa
 
 To run all examples together:
 
-```
+```bash
+# Bun is required for development (see CONTRIBUTING.md for install instructions)
 npm install
 npm run examples:start
 ```