- Refactor controller to not require importing engine.layers (which imports PIL)
- Add set_effect_chain_ref for external chain registration
- Fix cmdline to use new ref mechanism
- Add PerformanceMonitor to collect per-effect timings
- Track effect duration (ms), buffer chars in/out per frame
- Store last 60 frames in ring buffer
- Add /effects stats NTFY command to view performance data
- Add tests for performance monitoring system