feat: complete Phase 8.3 - recording settings (input gain, mono/stereo, sample rate)

Recording Settings (Phase 8.3):
- Added input gain control (0.0-2.0 with dB display)
- Real-time gain adjustment via GainNode during recording
- Mono/Stereo recording mode selection
- Sample rate matching (44.1kHz, 48kHz, 96kHz)
- Mono conversion averages all channels when enabled
- Recording settings panel shown when track is armed

Components Created:
- RecordingSettings.tsx: Settings panel with gain slider, mono/stereo toggle, sample rate buttons

Components Modified:
- useRecording hook: Added settings state and GainNode integration
- AudioEditor: Pass recording settings to TrackList
- TrackList: Forward settings to Track components
- Track: Show RecordingSettings when armed for recording

Technical Details:
- GainNode inserted between source and analyser in recording chain
- Real-time gain updates via gainNode.gain.value
- AudioContext created with target sample rate
- Mono conversion done post-recording by averaging channels
- Settings persist during recording session

Phase 8 Complete:
- ✅ Phase 8.1: Audio Input
- ✅ Phase 8.2: Recording Controls (punch/overdub)
- ✅ Phase 8.3: Recording Settings
- 📋 Phase 9: Automation (NEXT)

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

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

components/tracks/Track.tsx

@@ -10,6 +10,8 @@ import { EffectBrowser } from '@/components/effects/EffectBrowser';
 import { EffectDevice } from '@/components/effects/EffectDevice';
 import { createEffect, type EffectType } from '@/lib/audio/effects/chain';
 import { InputLevelMeter } from '@/components/recording/InputLevelMeter';
+import { RecordingSettings } from '@/components/recording/RecordingSettings';
+import type { RecordingSettings as RecordingSettingsType } from '@/lib/hooks/useRecording';
 
 export interface TrackProps {
   track: TrackType;
@@ -36,6 +38,10 @@ export interface TrackProps {
   isRecording?: boolean;
   recordingLevel?: number;
   playbackLevel?: number;
+  recordingSettings?: RecordingSettingsType;
+  onInputGainChange?: (gain: number) => void;
+  onRecordMonoChange?: (mono: boolean) => void;
+  onSampleRateChange?: (sampleRate: number) => void;
 }
 
 export function Track({
@@ -63,6 +69,10 @@ export function Track({
   isRecording = false,
   recordingLevel = 0,
   playbackLevel = 0,
+  recordingSettings,
+  onInputGainChange,
+  onRecordMonoChange,
+  onSampleRateChange,
 }: TrackProps) {
   const canvasRef = React.useRef<HTMLCanvasElement>(null);
   const containerRef = React.useRef<HTMLDivElement>(null);
@@ -584,6 +594,16 @@ export function Track({
                 })()}
               </span>
             </div>
+
+            {/* Recording Settings - Show when track is armed */}
+            {track.recordEnabled && recordingSettings && onInputGainChange && onRecordMonoChange && onSampleRateChange && (
+              <RecordingSettings
+                settings={recordingSettings}
+                onInputGainChange={onInputGainChange}
+                onRecordMonoChange={onRecordMonoChange}
+                onSampleRateChange={onSampleRateChange}
+              />
+            )}
           </>
         )}
       </div>