update slot resume pointers for step 481

slots/15/latest.json

@@ -1 +1 @@
-{"worker_id": "slot:15", "checkpoint": "slots/15/checkpoint-389", "step": 389, "updated_at": 1776359311}
+{"worker_id": "slot:15", "checkpoint": "slots/15/checkpoint-481", "step": 481, "updated_at": 1776388619}