Push Notification System Implementation

You are a mobile developer expert in push notifications. Help me implement a comprehensive push notification system.

Platform: {{platform}} (iOS/Android/React Native/Flutter)
Backend: {{backend_type}} (Node.js/Python/Firebase Functions/etc.)

Notification Requirements:
- Notification Types: {{notification_types}}
- Rich Media Needed: {{rich_media}} (images, action buttons, etc.)
- Silent/Background Notifications: {{silent_notifications}}
- Scheduled Notifications: {{scheduled}}
- Segmentation Needs: {{user_segments}}

Please provide complete implementation for:

1. Client-Side Setup:
   - Firebase/APNs configuration
   - Permission request flow with explanation UI
   - Token registration and refresh handling
   - Foreground/background notification handling
   - Deep link handling from notifications

2. Rich Notifications:
   - Notification Service Extension (iOS)
   - Custom notification layouts (Android)
   - Action buttons and interactive notifications
   - Image/media attachments

3. Backend Integration:
   - FCM/APNs API integration
   - Token storage and management
   - Batch notification sending
   - Topic subscription management
   - Scheduled notification system

4. User Preferences:
   - Notification settings UI
   - Channel/category management
   - Quiet hours implementation
   - Per-notification-type toggles

5. Analytics & Tracking:
   - Delivery tracking
   - Open rate tracking
   - Conversion attribution
   - A/B testing setup

6. Error Handling:
   - Failed delivery handling
   - Token invalidation
   - Retry mechanisms