docs: update Phase 9 automation progress in PLAN.md

Completed automation features:
- ✅ 9.1: Automation lanes UI (volume, pan, effects with dropdown)
- ✅ 9.2: Automation points (add/remove/drag/select/delete)
- ✅ UI: Automation modes selector (R/W/T/L)

Remaining automation work:
- ⏳ 9.3: Real-time automation playback
- ⏳ 9.3: Automation recording
- ⏳ 9.3: Automation modes implementation
- ⏳ 9.2: Copy/paste automation, bezier curves

PLAN.md

@@ -626,21 +626,28 @@ audio-ui/
 ### Phase 9: Automation
 
 #### 9.1 Automation Lanes
-- [ ] Show/Hide automation lanes per track
-- [ ] Automation lane for volume
-- [ ] Automation lane for pan
-- [ ] Automation lanes for effect parameters
+- [x] Show/Hide automation lanes per track
+- [x] Automation lane for volume
+- [x] Automation lane for pan
+- [x] Automation lanes for effect parameters
+- [x] Single automation lane with parameter dropdown selector
+- [x] Automation controls in left sidebar (matching track controls)
+- [x] Perfect alignment with waveform width
 
 #### 9.2 Automation Points
-- [ ] Add/Remove automation points
-- [ ] Drag automation points
-- [ ] Automation curves (linear/bezier/step)
+- [x] Add/Remove automation points
+- [x] Drag automation points
+- [x] Automation curves (linear/step support)
+- [x] Select automation points
+- [x] Delete with keyboard (Delete/Backspace)
 - [ ] Copy/Paste automation
+- [ ] Bezier curves
 
 #### 9.3 Automation Playback
 - [ ] Real-time automation during playback
 - [ ] Automation recording (write mode)
-- [ ] Automation editing modes (read/write/touch/latch)
+- [x] Automation editing modes UI (read/write/touch/latch)
+- [ ] Automation modes implementation
 
 ### Phase 10: Analysis Tools