feat: add pan knob icon to Pan label

Added Move icon (crosshair/knob) to Pan label to match Volume's icon.
Now both controls have visual icons for better UI consistency.

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

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

components/tracks/Track.tsx

@@ -1,7 +1,7 @@
 'use client';
 
 import * as React from 'react';
-import { Volume2, VolumeX, Headphones, Trash2, ChevronDown, ChevronRight } from 'lucide-react';
+import { Volume2, VolumeX, Headphones, Trash2, ChevronDown, ChevronRight, Move } from 'lucide-react';
 import type { Track as TrackType } from '@/types/track';
 import { Button } from '@/components/ui/Button';
 import { Slider } from '@/components/ui/Slider';
@@ -283,7 +283,10 @@ export function Track({
 
             {/* Pan */}
             <div className="flex items-center gap-2">
-              <label className="text-xs text-muted-foreground w-16 flex-shrink-0">Pan</label>
+              <label className="text-xs text-muted-foreground flex items-center gap-1 w-16 flex-shrink-0">
+                <Move className="h-3 w-3" />
+                Pan
+              </label>
               <div className="flex-1">
                 <Slider
                   value={track.pan}