Rename Pro directory license files to NOTICE

- Rename lib/react_on_rails/pro/LICENSE.md → NOTICE
- Rename node_package/src/pro/LICENSE.md → NOTICE
- Follows convention for subdirectory licensing notices
- Avoids confusion with main repository LICENSE.md

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

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

Author: justin808