- Add PolynomialLR scheduler with configurable polynomial decay
- Add CyclicalLR with triangular, triangular2, and exponential range modes
- Add WarmupScheduler as generic wrapper for any base scheduler
- Add LRScheduleVisualizer for ASCII visualization of schedules
- Enhanced ScheduledOptimizer with convenience factory methods
- Add comprehensive advanced_lr_scheduling.rs example
- Update documentation and README with new features
- Add comprehensive test coverage for all new schedulers
- Bump version to 0.4.0