Add Haptic Feedback for In-Tune State

[pbalduino]

Description

Provide haptic feedback when string is perfectly in tune

Priority

🟡 Medium

Category

Accessibility

Details

• Add haptic feedback when frequency is within ±1.5 cents
• Use appropriate haptic feedback pattern for in-tune state
• Ensure feedback doesn't repeat too frequently
• Make haptic feedback optional in settings

Files Affected

• lib/screens/tuner_screen.dart
• lib/screens/settings_screen.dart

Acceptance Criteria

• Haptic feedback triggers when perfectly in tune
• Feedback pattern is distinct and recognizable
• Setting exists to enable/disable haptic feedback
• No performance impact when disabled

Task ID: A11Y-001

[pbalduino]

Haptic Feedback Implementation Complete

Successfully implemented haptic feedback for in-tune states to enhance accessibility:

✅ Haptic Trigger: Light impact feedback when frequency is within ±1.5 cents
✅ Smart Logic: Only triggers on state change (prevents repeated feedback)
✅ User Control: Setting available to enable/disable haptic feedback
✅ Performance: No impact when disabled, efficient state tracking

Technical Implementation:

• Added HapticFeedback.lightImpact() integration
• State tracking with _lastGaugeStatus to prevent spam
• User preference system with UserPreferences.hapticsEnabled
• Proper cleanup and lifecycle management

Enhanced Accessibility:
Musicians can now feel when their instrument is perfectly in tune, making the app more accessible for users who rely on tactile feedback or use the app in environments where visual feedback may be limited.