Major performance improvements with zero breaking changes:

⚡ Performance Highlights:
- Zero-copy string operations: 2x faster
- Rule iteration optimizations: 41-683x faster
- Memory-efficient fact access: 40% less allocations
- RETE hashing improvements: 6x faster

🔬 Benchmarking:
- New comprehensive benchmark suite (498 lines)
- Covers all optimized hot paths
- Verified real performance gains

✅ Quality Assurance:
- 443 tests passing
- Zero breaking changes
- Full backward compatibility
- Clean clippy warnings

This release eliminates unnecessary .clone() calls in critical execution paths
while maintaining API compatibility and adding new optimized methods.