fix 轨迹明细操作人默认系统

src/SJZY.Track.Application/EventHandlers/TrackUpsertEventHandler.cs

@@ -129,7 +129,7 @@ public class TrackUpsertEventHandler : ITransientDependency, ICapSubscribe
                 IsCanDelete = false,
                 OriginTrackContent = @event.OriginTrackContent,
                 OriginTrackData = @event.OriginTrackData,
-                CreateUser = @event.OperationMan,
+                CreateUser = @event.OperationMan ?? "系统",
                 CreateTime = DateTime.Now
             };