docs: update Phase 9 automation completion status

Phase 9 automation is now mostly complete!

✅ Completed:
- 9.1: Automation lanes UI (volume, pan, effects with dropdown selector)
- 9.2: Automation points (add/remove/drag/select/delete)
- 9.3: Real-time automation playback (volume, pan, effects)
  - Continuous evaluation via requestAnimationFrame
  - Proper parameter range conversion
  - Works with all effect types

⏳ Remaining:
- Automation recording (write mode)
- Mode-specific recording behavior (touch/latch)
- Copy/paste automation
- Bezier curve support

The automation system is now fully functional for playback!

PLAN.md

@@ -644,10 +644,14 @@ audio-ui/
 - [ ] Bezier curves
 
 #### 9.3 Automation Playback
-- [ ] Real-time automation during playback
+- [x] Real-time automation during playback
+- [x] Automation for volume and pan
+- [x] Automation for effect parameters
+- [x] Continuous evaluation via requestAnimationFrame
+- [x] Proper parameter range conversion
 - [ ] Automation recording (write mode)
 - [x] Automation editing modes UI (read/write/touch/latch)
-- [ ] Automation modes implementation
+- [ ] Automation modes recording implementation (write/touch/latch)
 
 ### Phase 10: Analysis Tools