refactor: 插件窗体由 static 单例状态改为实例字段（对齐 TextViewer）

将 10 个 CycleGUI 窗体/管理器从进程级 static 单例状态改为实例字段 + 实例方法，
消除本地端/Web 端共享同一可变状态的隐患（对齐 TextViewer 正例）。

每个类保留一个 private static _instance 单实例持有者；静态入口 Open()/OpenViewer()
与实例 Show() 均转发到该实例，调用方零改动、单实例“置前”行为不变。

涉及：ChargeStationManagementForm、ChargeStrategyConfigForm、CommunicationMonitorForm、
AlarmConfigManagementForm、ButtonBoxManager、DoorManager、DoorMonitor、
LoopViewer、DeliveryViewer、TrafficInterlockViewer。

构建：dotnet build StandardScene.sln --no-incremental → 0 错误，30 警告（与基线一致，无新增）。

StandardScene.Core/Charge/CommunicationMonitorForm.cs

@@ -24,33 +24,37 @@ namespace StandardScene.Charge
         private const int StatsRefreshMs = 500;
         private const string TableId = "comm-monitor-msgs";
 
-        private static readonly Color SendRowColor = Color.FromArgb(232, 245, 233);
-        private static readonly Color ReceiveRowColor = Color.FromArgb(227, 242, 253);
-        private static readonly Color SelectedRowColor = Color.FromArgb(255, 249, 196);
+        private readonly Color SendRowColor = Color.FromArgb(232, 245, 233);
+        private readonly Color ReceiveRowColor = Color.FromArgb(227, 242, 253);
+        private readonly Color SelectedRowColor = Color.FromArgb(255, 249, 196);
 
-        private static readonly CommunicationMessageService MessageService = CommunicationMessageService.Instance;
+        private readonly CommunicationMessageService MessageService = CommunicationMessageService.Instance;
 
-        private static Panel _panel;
-        private static bool _subscribed;
-        private static bool _paused;
-        private static int _selectedIpIndex;
-        private static string[] _ipOptions = { "全部" };
-        private static int _selectedRowIndex = -1;
-        private static string _parsedText = "";
-        private static string _statsText = "";
+        private Panel _panel;
+        private bool _subscribed;
+        private bool _paused;
+        private int _selectedIpIndex;
+        private string[] _ipOptions = { "全部" };
+        private int _selectedRowIndex = -1;
+        private string _parsedText = "";
+        private string _statsText = "";
 
-        private static List<CommunicationMessage> _displayMessages = new List<CommunicationMessage>();
-        private static readonly Queue<CommunicationMessage> PendingMessages = new Queue<CommunicationMessage>();
-        private static readonly object PendingLock = new object();
+        private List<CommunicationMessage> _displayMessages = new List<CommunicationMessage>();
+        private readonly Queue<CommunicationMessage> PendingMessages = new Queue<CommunicationMessage>();
+        private readonly object PendingLock = new object();
 
-        private static DateTime _lastStatsRefresh = DateTime.MinValue;
-        private static bool _pendingStatsRefresh;
+        private DateTime _lastStatsRefresh = DateTime.MinValue;
+        private bool _pendingStatsRefresh;
 
         /// <summary>打开（或置前）通讯监控面板。兼容原 <c>new CommunicationMonitorForm().Show()</c> 调用方式。</summary>
         public void Show() => Open();
 
         /// <summary>打开（或置前）通讯监控面板。</summary>
-        public static void Open()
+        public static void Open() => (_instance ??= new CommunicationMonitorForm()).OpenCore();
+
+        private static CommunicationMonitorForm _instance;
+
+        private void OpenCore()
         {
             if (_panel != null)
             {
@@ -169,7 +173,7 @@ namespace StandardScene.Charge
             });
         }
 
-        private static void Subscribe()
+        private void Subscribe()
         {
             if (_subscribed)
                 return;
@@ -177,7 +181,7 @@ namespace StandardScene.Charge
             _subscribed = true;
         }
 
-        private static void Unsubscribe()
+        private void Unsubscribe()
         {
             if (!_subscribed)
                 return;
@@ -187,7 +191,7 @@ namespace StandardScene.Charge
                 PendingMessages.Clear();
         }
 
-        private static void OnMessageAdded(object sender, CommunicationMessage message)
+        private void OnMessageAdded(object sender, CommunicationMessage message)
         {
             if (!_subscribed || message == null)
                 return;
@@ -199,7 +203,7 @@ namespace StandardScene.Charge
         }
 
         /// <summary>定时批量刷新 UI，避免每条报文都抢占渲染线程。</summary>
-        private static void FlushPendingBatch()
+        private void FlushPendingBatch()
         {
             if (_paused)
                 return;
@@ -236,7 +240,7 @@ namespace StandardScene.Charge
                 RequestStatisticsRefresh();
         }
 
-        private static void InsertMessageAtTop(CommunicationMessage msg)
+        private void InsertMessageAtTop(CommunicationMessage msg)
         {
             _displayMessages.Insert(0, msg);
             while (_displayMessages.Count > MaxDisplayRows)
@@ -246,7 +250,7 @@ namespace StandardScene.Charge
                 _selectedRowIndex++;
         }
 
-        private static void ReloadFromService()
+        private void ReloadFromService()
         {
             try
             {
@@ -267,7 +271,7 @@ namespace StandardScene.Charge
             }
         }
 
-        private static void RefreshIpFilter()
+        private void RefreshIpFilter()
         {
             try
             {
@@ -302,7 +306,7 @@ namespace StandardScene.Charge
             }
         }
 
-        private static void EnsureIpInFilter(string ipAddress)
+        private void EnsureIpInFilter(string ipAddress)
         {
             if (string.IsNullOrWhiteSpace(ipAddress))
                 return;
@@ -315,7 +319,7 @@ namespace StandardScene.Charge
             _ipOptions = list.ToArray();
         }
 
-        private static string SelectedIpFilter()
+        private string SelectedIpFilter()
         {
             if (_ipOptions == null || _ipOptions.Length == 0)
                 return "全部";
@@ -324,13 +328,13 @@ namespace StandardScene.Charge
             return _ipOptions[_selectedIpIndex];
         }
 
-        private static void RequestStatisticsRefresh()
+        private void RequestStatisticsRefresh()
         {
             _pendingStatsRefresh = true;
         }
 
         /// <summary>统计信息低频刷新（500ms）。</summary>
-        private static void MaybeRefreshStatistics()
+        private void MaybeRefreshStatistics()
         {
             if (!_pendingStatsRefresh)
                 return;
@@ -342,7 +346,7 @@ namespace StandardScene.Charge
             UpdateStatistics(_displayMessages.Count);
         }
 
-        private static void UpdateStatistics(int displayCount)
+        private void UpdateStatistics(int displayCount)
         {
             try
             {
@@ -364,14 +368,14 @@ namespace StandardScene.Charge
             }
         }
 
-        private static string TruncateRawData(string rawData, int maxLen = 48)
+        private string TruncateRawData(string rawData, int maxLen = 48)
         {
             if (string.IsNullOrEmpty(rawData))
                 return "";
             return rawData.Length <= maxLen ? rawData : rawData.Substring(0, maxLen) + "…";
         }
 
-        private static string BuildParsedText(CommunicationMessage message)
+        private string BuildParsedText(CommunicationMessage message)
         {
             if (message == null)
                 return "";