docs: Add quickstart guide for kernel optimizations

Added OPTIMIZATIONS_QUICKSTART.md with:
- Quick examples for all 8 optimizations
- Integration patterns (drop-in, wrapper, progressive)
- Performance tips and tuning guidelines
- Troubleshooting common issues
- Monitoring and metrics guidance

This provides a practical getting-started guide for developers.

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot