Remove REACT_ON_RAILS_IMPROVEMENTS.md - will create as GitHub issue instead

This roadmap document is better suited as a GitHub issue/discussion
rather than a file in the repository. It outlines strategic planning
and future improvements that would benefit from community discussion.

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

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

Author: justin808