feat: redesign track and master controls with integrated fader+meters+pan

Unified design language across all tracks and master section:
- Created TrackFader component: vertical fader with horizontal meter bars
- Created TrackControls: integrated pan + fader + mute in compact layout
- Created MasterFader: similar design but larger for master output
- Created MasterControls: master version with pan + fader + mute
- Updated Track component to use new TrackControls
- Updated PlaybackControls to use new MasterControls
- Removed old VerticalFader and separate meter components

New features:
- Horizontal peak/RMS meter bars behind fader (top=peak, bottom=RMS)
- Color-coded meters (green/yellow/red based on dB levels)
- dB scale labels and numeric readouts
- Integrated mute button in controls
- Consistent circular pan knobs
- Professional DAW-style channel strip appearance
- Master section includes clip indicator

Visual improvements:
- Unified design across all tracks and master
- Compact vertical layout saves space
- Real-time level monitoring integrated with volume control
- Smooth animations and transitions

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

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

components/editor/PlaybackControls.tsx

@@ -1,10 +1,9 @@
 'use client';
 
 import * as React from 'react';
-import { Play, Pause, Square, SkipBack, Volume2, VolumeX, Circle, AlignVerticalJustifyStart, AlignVerticalJustifyEnd, Layers } from 'lucide-react';
+import { Play, Pause, Square, SkipBack, Circle, AlignVerticalJustifyStart, AlignVerticalJustifyEnd, Layers } from 'lucide-react';
 import { Button } from '@/components/ui/Button';
-import { Slider } from '@/components/ui/Slider';
-import { MasterMeter } from '@/components/controls/MasterMeter';
+import { MasterControls } from '@/components/controls/MasterControls';
 import { cn } from '@/lib/utils/cn';
 
 export interface PlaybackControlsProps {
@@ -13,11 +12,14 @@ export interface PlaybackControlsProps {
   currentTime: number;
   duration: number;
   volume: number;
+  pan?: number;
   onPlay: () => void;
   onPause: () => void;
   onStop: () => void;
   onSeek: (time: number, autoPlay?: boolean) => void;
   onVolumeChange: (volume: number) => void;
+  onPanChange?: (pan: number) => void;
+  onMuteToggle?: () => void;
   disabled?: boolean;
   className?: string;
   currentTimeFormatted?: string;
@@ -45,11 +47,14 @@ export function PlaybackControls({
   currentTime,
   duration,
   volume,
+  pan = 0,
   onPlay,
   onPause,
   onStop,
   onSeek,
   onVolumeChange,
+  onPanChange,
+  onMuteToggle,
   disabled = false,
   className,
   currentTimeFormatted,
@@ -70,9 +75,6 @@ export function PlaybackControls({
   masterIsClipping = false,
   onResetClip,
 }: PlaybackControlsProps) {
-  const [isMuted, setIsMuted] = React.useState(false);
-  const [previousVolume, setPreviousVolume] = React.useState(volume);
-
   const handlePlayPause = () => {
     if (isPlaying) {
       onPause();
@@ -81,26 +83,6 @@ export function PlaybackControls({
     }
   };
 
-  const handleMuteToggle = () => {
-    if (isMuted) {
-      onVolumeChange(previousVolume);
-      setIsMuted(false);
-    } else {
-      setPreviousVolume(volume);
-      onVolumeChange(0);
-      setIsMuted(true);
-    }
-  };
-
-  const handleVolumeChange = (newVolume: number) => {
-    onVolumeChange(newVolume);
-    if (newVolume === 0) {
-      setIsMuted(true);
-    } else {
-      setIsMuted(false);
-    }
-  };
-
   const progress = duration > 0 ? (currentTime / duration) * 100 : 0;
 
   return (
@@ -284,41 +266,21 @@ export function PlaybackControls({
           )}
         </div>
 
-        {/* Volume Control & Master Meter */}
-        <div className="flex items-center gap-4">
-          {/* Master Meter */}
-          <MasterMeter
+        {/* Master Controls */}
+        {onPanChange && onMuteToggle && (
+          <MasterControls
+            volume={volume}
+            pan={pan}
             peakLevel={masterPeakLevel}
             rmsLevel={masterRmsLevel}
             isClipping={masterIsClipping}
+            isMuted={volume === 0}
+            onVolumeChange={onVolumeChange}
+            onPanChange={onPanChange}
+            onMuteToggle={onMuteToggle}
             onResetClip={onResetClip}
           />
-
-          {/* Volume Control */}
-          <div className="flex items-center gap-3 min-w-[200px]">
-            <Button
-              variant="ghost"
-              size="icon"
-              onClick={handleMuteToggle}
-              title={isMuted ? 'Unmute' : 'Mute'}
-            >
-              {isMuted || volume === 0 ? (
-                <VolumeX className="h-5 w-5" />
-              ) : (
-                <Volume2 className="h-5 w-5" />
-              )}
-            </Button>
-
-            <Slider
-              value={volume}
-              onChange={handleVolumeChange}
-              min={0}
-              max={1}
-              step={0.01}
-              className="flex-1"
-            />
-          </div>
-        </div>
+        )}
       </div>
     </div>
   );