Update React 19 upgrade guide with direct support contact

- Change commercial support link from web form to direct email
- Makes it easier for users to reach out for professional support

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

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

Author: justin808

docs/upgrading/react-19-upgrade-guide.md

@@ -412,7 +412,7 @@ If you encounter issues during the upgrade:
 1. **Check the Issues**: [React on Rails GitHub Issues](https://github.com/shakacode/react_on_rails/issues)
 2. **Community Forum**: [ShakaCode Forum](https://forum.shakacode.com)
 3. **Discord**: [React on Rails Discord](https://discord.gg/reactonrails)
-4. **Commercial Support**: Contact [ShakaCode](https://www.shakacode.com/contact) for professional support
+4. **Commercial Support**: Contact [ShakaCode](mailto:justin@shakacode.com) for professional support
 
 ## Changelog