docs: update CLAUDE.md, README.md, and GitHub description to current state

Major documentation updates to reflect all merged features:

CLAUDE.md Updates:
- Updated to 2025-11-08, branch: main, status: Production-Ready
- Added Cost Optimizer feature prominently (90% cost savings)
- Added complete authentication system details
- Added Chinese LLM support section
- Updated project stats and metrics
- Added all new documentation references
- Removed outdated MCP server references

README.md Updates:
- Complete rewrite with current feature set
- Highlighted Cost Optimizer as revolutionary feature
- Added "By The Numbers" section with all stats
- Added complete authentication details
- Added Chinese LLM support
- Added comprehensive usage examples
- Added deployment guides
- Updated roadmap with completed phases

GITHUB_DESCRIPTION_UPDATE.md (NEW):
- Instructions for updating GitHub About section
- New description highlighting all features
- Removes outdated MCP references (Task Master AI, Serena, Shrimp)
- Emphasizes production-ready status
- Highlights 90% cost savings
- Celebrates building on mobile with Claude Code
- Includes topics/tags for repository

Key Changes:
✅ Cost Optimizer feature highlighted (90% savings, $45→$4.50/month)
✅ Complete authentication system documented
✅ Chinese LLM support detailed (Qwen, DeepSeek, ChatGLM, etc.)
✅ Production-ready status emphasized
✅ 4,500+ lines of documentation referenced
✅ Skills-First approach explained
✅ All merged work from mobile sessions preserved

Ready for GitHub push and repository description update!

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

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

Author: ScientiaCapital