feat: Implement regression analysis with historical comparison

- Add HistoricalResults and TimestampedResults structures for baseline data management
- Implement complete performance regression analysis with 5% improvement/regression thresholds
- Provide actionable recommendations for detected improvements, regressions, and new operations
- Add comprehensive test coverage for regression analysis functionality with baseline comparison
- Fix all readme code examples to be compilable with proper error handling and imports
- Create task backlog entry for future regression analysis enhancements

Author: Wandalen