fix: skip GC in sched_end_session when live_jobs allocation fails (OOM safety)

src/scheduler/src/scheduler.c

@@ -822,6 +822,12 @@ void sched_end_session(xce_scheduler_t* sched)
         }
     }
 
+    if (live_jobs == NULL) {
+        /* OOM: cannot safely GC — skip to avoid sweeping nodes still in use */
+        atomic_store_explicit(&sched->staging_merge_complete, 1, memory_order_release);
+        return;
+    }
+
     /* Mark phase */
     gc_clear_marks();
     for (int i = 0; i < njobs; i++) {