Create comprehensive README.md showcasing all new CedarMapper features

Major documentation transformation:
- Complete README rewrite from scratch with professional GitHub-ready presentation
- Added real command outputs for all new features (YAML, analytics columns, sorting)
- Documented structured YAML output with front matter for LLM consumption
- Showcased advanced analytics columns: Depth, Files, Dirs, Avg-W, Avg-S with real examples
- Comprehensive 13-key sorting reference table with practical use cases
- Git-style line limiting examples using familiar -N syntax
- Performance optimization documentation (Linux tools, conditional computation)
- Practical workflows section for LLM analysis, code review, documentation, and performance auditing
- Competitive analysis table vs tree, fd/find, and llm-repo-tools
- Complete command reference with all 28+ CLI options
- Installation, development, testing, and contribution guidelines
- Troubleshooting FAQ with common questions and performance tips

The README now positions CedarMapper as a professional-grade repository analysis tool specifically designed for LLM workflows, with 374 lines of comprehensive documentation including real examples from the actual codebase.

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

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

Author: elifarley