fix: Mission.Stop 与 VDA ForceStop 改为 override

避免通过基类引用调用时走到空实现，隐藏的 Stop/ForceStop 无法真正停进程。

Co-authored-by: Cursor <cursoragent@cursor.com>

StandardScene.Core/Chained/ChainedDeliveryMission.cs

@@ -676,7 +676,7 @@ namespace StandardScene.Chained
         /// 关闭调度进程，取消后台循环
         /// </summary>
         [MethodMember(Name = "关闭进程", Description = "关闭任务维护进程")]
-        public void Stop()
+        public override void Stop()
         {
             status.status = "关闭中";
             _started = false;

StandardScene.Core/Scheduler/HeartBeatMission.cs

@@ -62,7 +62,7 @@ namespace StandardScene.Scheduler
         }
 
         [MethodMember(Name = "关闭进程", Description = "停止下发心跳")]
-        public void Stop()
+        public override void Stop()
         {
             _started = false;
             _myThread?.Join(2000);

StandardScene.Core/Scheduler/NodeIsEnableMission.cs

@@ -116,7 +116,7 @@ namespace StandardScene.Scheduler
         }
 
         [MethodMember(Name = "关闭机构进程", Description = "关闭机构进程")]
-        public void Stop()
+        public override void Stop()
         {
             started = false;
             status.status = $"已停止-循环";

StandardScene.Core/Scheduler/RegionalTrafficControlMission.cs

@@ -103,7 +103,7 @@ namespace StandardScene.Scheduler
         /// 停止进程
         /// </summary>
         [MethodMember(Name = "停止进程", Description = "停止区域流量监控")]
-        public void Stop()
+        public override void Stop()
         {
             if (!started)
             {

StandardScene.Core/Scheduler/SecuritySignalMission.cs

@@ -171,7 +171,7 @@ namespace StandardScene.Scheduler
         }
 
         [MethodMember(Name = "关闭机构进程", Description = "关闭机构进程")]
-        public void Stop()
+        public override void Stop()
         {
             started = false;
             status.status = $"已停止-循环";

StandardScene.Protocol.VDA5050/VDACar/VDA5050Car.cs

@@ -712,7 +712,7 @@ namespace StandardScene.CarTypes
         [MethodMember(Name = "立即强制结束",
             RequiresPlatformConfirm = true,
             ConfirmMessage = "确定强制结束该车上的作业并下线？")]
-        public void ForceStop()
+        public override void ForceStop()
         {
             AppendDebug("Clumsy Restarted");
             NoSchedule(true);