新增 scene.signal 信号交互插件，落地 PLC 握手与扫车放行。

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

StandardScene.Signal/Model/PlcStationSnapshot.cs

@@ -0,0 +1,19 @@
+using System.ComponentModel;
+
+namespace StandardScene.Signal.Model
+{
+    /// <summary>单个机构运行态快照，供 MissionStatus / 监视面板展示。</summary>
+    public class PlcStationSnapshot
+    {
+        [DisplayName("机构")] public string JgName { get; set; } = "";
+        [DisplayName("连接")] public bool IsConnected { get; set; }
+        [DisplayName("读信号")] public string ReadSignal { get; set; } = "";
+        [DisplayName("写信号")] public string WriteSignal { get; set; } = "";
+        [DisplayName("回读写值")] public string ReadWriteSignal { get; set; } = "";
+        [DisplayName("机构内车")] public int InAgvNo { get; set; }
+        [DisplayName("请求进入车")] public int RequestInAgvNo { get; set; }
+        [DisplayName("写入成功")] public bool WriteSuccess { get; set; }
+        [DisplayName("心跳")] public bool Heart { get; set; }
+        [DisplayName("最近错误")] public string LastError { get; set; } = "";
+    }
+}