Grants test: compare the record against a deep copy, so a written holding fails it (issue 1966)

Claude-Session: https://claude.ai/code/session_01NcbgfFfQ4Z9UE5jK32PmE5

modules/mesh-grants/grants_test.go

@@ -1325,7 +1325,11 @@ func TestGrants(t *testing.T) {
 					in.Manifests[c] = claimer(c)
 					in.Assigned["b"] = append(in.Assigned["b"], c)
 				}
-				before := in.Placed
+				before := maps.Clone(in.Placed)
+				for node, p := range before {
+					p.Holds = slices.Clone(p.Holds)
+					before[node] = p
+				}
 				recs, gaps := grants.ListRecords(in)
 				users, refusedU, err := grants.ComposeEach(recs)
 				if len(refusedU) != 0 {