fix(users): add eventify_id__icontains to UserListView search filter

EVT-XXXXXXXX searches were returning no results because the Q filter
only covered first_name, last_name, email, username, phone_number.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

admin_api/views.py

@@ -595,7 +595,8 @@ class UserListView(APIView):
                 Q(last_name__icontains=search) |
                 Q(email__icontains=search) |
                 Q(username__icontains=search) |
-                Q(phone_number__icontains=search)
+                Q(phone_number__icontains=search) |
+                Q(eventify_id__icontains=search)
             )
 
         # Status filter