feat: Add management command to clean old registrations

Implements a Django management command to automatically
remove outdated user registrations. Cleans 'started'
registrations older than 48 hours and 'denied' or
'approved' registrations older than 30 days, for
privacy reasons.

src/synapse_registration/registration/management/commands/cleanup.py

@@ -0,0 +1,26 @@
+from django.core.management.base import BaseCommand
+
+from ...models import UserRegistration
+
+from datetime import timedelta, datetime
+
+
+class Command(BaseCommand):
+    help = "Clean up old user registrations"
+
+    def handle(self, *args, **options):
+        # Remove all registrations that are still in the "started" state after 48 hours
+        UserRegistration.objects.filter(
+            status=UserRegistration.STATUS_STARTED,
+            timestamp__lt=datetime.now() - timedelta(hours=48),
+        ).delete()
+
+        # Remove all registrations that are denied or approved after 30 days
+        UserRegistration.objects.filter(
+            status__in=[UserRegistration.STATUS_DENIED, UserRegistration.STATUS_APPROVED],
+            timestamp__lt=datetime.now() - timedelta(days=30),
+        ).delete()
+
+        self.stdout.write(
+            self.style.SUCCESS("Successfully cleaned up old user registrations")
+        )