feat: implement Phase 9.1 - Automation lanes UI

Added comprehensive automation lane UI with Ableton-style design:

**Automation Components:**
- AutomationLane: Canvas-based rendering with grid lines, curves, and points
- AutomationHeader: Parameter name, mode selector, value display
- AutomationPoint: Interactive draggable points with hover states

**Automation Utilities:**
- createAutomationLane/Point: Factory functions
- evaluateAutomationLinear: Interpolation between points
- formatAutomationValue: Display formatting with unit support
- addAutomationPoint/updateAutomationPoint/removeAutomationPoint

**Track Integration:**
- Added "A" toggle button in track control panel
- Automation lanes render below waveform
- Default lanes for Volume (orange) and Pan (green)
- Support for add/edit/delete automation points
- Click to add, drag to move, double-click to delete

**Visual Design:**
- Dark background with horizontal grid lines
- Colored curves with semi-transparent fill (20% opacity)
- 4-6px automation points, 8px on hover
- Mode indicators (Read/Write/Touch/Latch) with colors
- Value labels and current value display

Ready for playback integration in next step.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

lib/audio/track-utils.ts

@@ -5,6 +5,7 @@
 import type { Track, TrackColor } from '@/types/track';
 import { DEFAULT_TRACK_HEIGHT, TRACK_COLORS } from '@/types/track';
 import { createEffectChain } from '@/lib/audio/effects/chain';
+import { createAutomationLane } from '@/lib/audio/automation-utils';
 
 /**
  * Generate a unique track ID
@@ -23,8 +24,10 @@ export function createTrack(name?: string, color?: TrackColor): Track {
   // Ensure name is always a string, handle cases where event objects might be passed
   const trackName = typeof name === 'string' && name.trim() ? name.trim() : 'New Track';
 
+  const trackId = generateTrackId();
+
   return {
-    id: generateTrackId(),
+    id: trackId,
     name: trackName,
     color: TRACK_COLORS[color || randomColor],
     height: DEFAULT_TRACK_HEIGHT,
@@ -36,7 +39,22 @@ export function createTrack(name?: string, color?: TrackColor): Track {
     recordEnabled: false,
     effectChain: createEffectChain(`${trackName} Effects`),
     automation: {
-      lanes: [],
+      lanes: [
+        createAutomationLane(trackId, 'volume', 'Volume', {
+          min: 0,
+          max: 1,
+          unit: 'dB',
+        }),
+        createAutomationLane(trackId, 'pan', 'Pan', {
+          min: -1,
+          max: 1,
+          formatter: (value: number) => {
+            if (value === 0) return 'C';
+            if (value < 0) return `${Math.abs(value * 100).toFixed(0)}L`;
+            return `${(value * 100).toFixed(0)}R`;
+          },
+        }),
+      ],
       showAutomation: false,
     },
     collapsed: false,