Add Python implementation of Business Central MCP Proxy

[DmitryKatson]

Summary

This PR adds a Python implementation of the Business Central MCP Proxy, providing a cross-platform alternative to the existing .NET version with simplified installation and setup.

Key Features

• PyPI-ready package: Published as bc-mcp-proxy (ready for Microsoft to publish under their PyPI account)
• Unified setup command: python -m bc_mcp_proxy setup handles configuration, authentication, and generates MCP client configs automatically
• Cross-platform: Works on Windows, macOS, and Linux
• Better IDE integration: Works seamlessly with Cursor, VS Code, and other Python-based MCP clients
• Same functionality: Provides identical MCP proxy capabilities as the .NET version

What's Included

• Core proxy implementation (bc_mcp_proxy/)
• Interactive setup flow with device-code authentication
• PyPI packaging configuration (pyproject.toml, MANIFEST.in, LICENSE)
• User-facing README following the .NET version structure
• Maintainer documentation and build scripts in maintainer/ folder
• Updated .gitignore to exclude Python build artifacts

Testing

The package has been tested on TestPyPI and verified to work end-to-end:

• ✅ Package builds and uploads successfully
• ✅ Installation from TestPyPI works
• ✅ Unified setup command functions correctly
• ✅ Proxy connects to Business Central successfully
• ✅ MCP clients can use the proxy via stdio

See samples/BcMCPProxyPython/maintainer/TESTING.md for detailed testing instructions.

Next Steps for Microsoft

1. Review the implementation
2. Test the package (instructions in maintainer/TESTING.md)
3. Publish to PyPI under Microsoft's account (instructions in maintainer/PUBLISHING.md)
4. Update any documentation as needed

Installation (for users, after publication)

python -m pip install --upgrade bc-mcp-proxy && python -m bc_mcp_proxy setup