docs: add comprehensive risk_manager documentation

- Create new API reference at docs/api/risk-manager.md
- Update risk management guide at docs/guide/risk.md
- Ensure 100% accuracy with current implementation
- Document all public APIs and methods
- Include working code examples throughout

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

Co-Authored-By: Claude <[email protected]>

Author: TexasCoding