update slot resume pointers for step 480

slots/6/latest.json

@@ -1 +1 @@
-{"worker_id": "slot:6", "checkpoint": "slots/6/checkpoint-405", "step": 405, "updated_at": 1776360698}
+{"worker_id": "slot:6", "checkpoint": "slots/6/checkpoint-480", "step": 480, "updated_at": 1776387907}