A node being lent says when a replica with nowhere to go is stopped

Tried on the PoC: lending cuda01, the one GPU node, its model had nowhere
else to go and waited out the drain's five-minute grace, while ctl slurm
status said only "1 replica(s) still to move off". It now says the time
that replica is stopped at. Also recorded: Slurm on a GPU node, tried on
cuda01 (gres, ConstrainDevices, accounting of gres/gpu).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/admin-api.openapi.json

@@ -12336,6 +12336,11 @@
           "replicas": {
             "type": "integer"
           },
+          "stops_by": {
+            "type": "string",
+            "format": "date-time",
+            "description": "StopsBy is, while it is being lent, when a replica still on it is stopped even with nowhere else to go: the drain's grace after the lend began. Zero when not known (a leader that took over meanwhile)."
+          },
           "slurm": {
             "$ref": "#/components/schemas/slurmsvc.Reported"
           },