- Install kreait/firebase-php SDK
- Create PushNotificationService with 3-tier credential resolution
  (system_settings → storage file → env var, graceful degradation)
- Auto-deactivate invalid/unregistered FCM tokens on send failure
- Add Push case to NotificationChannel enum
- Create 6 event listeners for push notifications:
  - AttendanceMarked → notify guardians (present/absent)
  - PaymentReceived → confirm payment to guardians
  - InvoiceCreated → alert guardians of new invoice
  - SessionCancelled → notify all group participants
  - EnrollmentCreated → confirm enrollment to guardians
  - EvaluationShared → notify guardians of new evaluation
- Register all listeners in EventServiceProvider (queued)
- Create NotificationController API endpoints:
  - GET notifications (paginated + unread count)
  - PATCH notifications/{id}/read
  - POST notifications/read-all
  - GET/POST notifications/preferences
- Create scheduled push commands:
  - push:session-reminder (every minute, 30min before session)
  - push:installment-due (daily, 1 and 3 days before due)
- Add channel_push column to notification_preferences
- Total: 20 API endpoints now live
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>