Switch to Sustainable Use License (fair-code model)

- Replace ISC license with Sustainable Use License v1.0
- Add LICENSE_FAQ.md explaining the fair-code approach
- Update package.json with new license identifier
- Add license headers to main entry point files
- Update README with clear license usage guidelines

Following n8n's licensing approach, this provides:
- Free use for internal business purposes
- Free use for personal/non-commercial projects
- Restrictions on hosting as a service
- Protection against commercial exploitation

No .ee. mechanism implemented yet - all features remain
freely available under the single license.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -300,8 +300,21 @@ n8n-mcp/
 
 ## License
 
-ISC
+This project is licensed under the [Sustainable Use License](LICENSE).
+
+### What does this mean?
+
+- ✅ **Free to use** for internal business purposes
+- ✅ **Free to use** for personal/non-commercial projects  
+- ✅ **Free to modify** for your own use
+- ✅ **Free to share** with others (non-commercially)
+- ❌ **Cannot** host as a service for others
+- ❌ **Cannot** include in commercial products without permission
+
+This is a "fair-code" license similar to n8n's approach. See [LICENSE_FAQ.md](LICENSE_FAQ.md) for more details.
 
 ## Support
 
-For issues and questions, please use the GitHub issue tracker.
+For issues and questions, please use the GitHub issue tracker.
+
+For commercial licensing inquiries, please open an issue with the "licensing" tag.