feat(events): harden registration checkout lifecycle

config/services/celery.py

@@ -38,6 +38,21 @@ app.conf.beat_schedule = {
         'schedule': crontab(hour=2, minute=0),
         'description': 'Runs daily at 02:00 UTC to cleanup notification retention.',
     },
+    'sweep-stale-payment-verifications': {
+        'task': 'apps.payments.sweep_stale_payment_verifications',
+        'schedule': crontab(minute='*/5'),
+        'description': 'Recovers old unresolved payment attempts with bounded gateway verification.',
+    },
+    'expire-stale-registration-checkouts': {
+        'task': 'apps.events.expire_stale_registration_checkouts',
+        'schedule': crontab(minute='*'),
+        'description': 'Releases seats from paid checkouts after their 15-minute window.',
+    },
+    'sweep-pending-refunds': {
+        'task': 'apps.payments.sweep_pending_refunds',
+        'schedule': crontab(minute='*/5'),
+        'description': 'Recovers pending transaction reversals and exposes exhausted attempts for admin review.',
+    },
 }
 
 CELERY_TASK_SOFT_TIME_LIMIT = 20