Replace Gorush with direct APNs/FCM integration

- Add direct APNs client using sideshow/apns2 for iOS push
- Add direct FCM client using legacy HTTP API for Android push
- Remove Gorush dependency (no external push server needed)
- Update all services/handlers to use new push.Client
- Update config for APNS_PRODUCTION flag

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

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

.env.example

@@ -29,21 +29,22 @@ EMAIL_HOST_PASSWORD=your-app-password
 DEFAULT_FROM_EMAIL=Casera <noreply@casera.com>
 
 # APNs Settings (iOS Push Notifications)
+# Direct APNs integration - no external push server needed
 APNS_AUTH_KEY_PATH=/path/to/AuthKey_XXXXXX.p8
 APNS_AUTH_KEY_ID=XXXXXXXXXX
 APNS_TEAM_ID=XXXXXXXXXX
 APNS_TOPIC=com.example.casera
-APNS_USE_SANDBOX=true
+APNS_PRODUCTION=false  # Set to true for production APNs, false for sandbox
 
 # FCM Settings (Android Push Notifications)
+# Direct FCM integration using legacy HTTP API
 FCM_SERVER_KEY=your-firebase-server-key
 
 # Worker Settings (Background Jobs)
-CELERY_BEAT_REMINDER_HOUR=20
-CELERY_BEAT_REMINDER_MINUTE=0
-
-# Gorush Push Notification Server
-GORUSH_URL=http://localhost:8088
+TASK_REMINDER_HOUR=20
+TASK_REMINDER_MINUTE=0
+OVERDUE_REMINDER_HOUR=9
+DAILY_DIGEST_HOUR=11
 
 # Admin Panel
 ADMIN_PORT=9000