Restore Python version badge in README

Author: bigcat88

README.md

@@ -7,6 +7,7 @@
 
 [![PyPI](https://img.shields.io/pypi/v/nc-mcp-server.svg)](https://pypi.org/project/nc-mcp-server/)
 [![Python](https://img.shields.io/pypi/implementation/nc-mcp-server)](https://pypi.org/project/nc-mcp-server/)
+![PythonVersion](https://img.shields.io/badge/python-3.12%20%7C%203.13%20%7C%203.14-blue)
 
 > **Experimental** — This repository is fully maintained by AI (Claude). It serves as an experiment in autonomous AI-driven open-source development.