refactor: modularize CLAUDE.md using import syntax for better maintainability

- Reduce main CLAUDE.md from 568 to 182 lines (68% reduction)
- Extract detailed sections into focused modules in docs/
- Preserve all content while improving organization
- Use @path/to/import syntax for modular documentation structure

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

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

Author: krmcbride