refactor(net): converge live session state reset

src/AcDream.UI.Abstractions/Panels/Chat/ChatVM.cs

@@ -116,6 +116,17 @@ public sealed class ChatVM
     /// </summary>
     public void Clear() => _log.Clear();
 
+    /// <summary>
+    /// Forget per-session reply/retell destinations while retaining the shared
+    /// transcript. Old character names must not become command targets after a
+    /// reconnect.
+    /// </summary>
+    public void ResetSessionTargets()
+    {
+        LastIncomingTellSender = null;
+        LastOutgoingTellTarget = null;
+    }
+
     /// <summary>
     /// Print the current framerate into chat. Used by
     /// <c>/framerate</c> / <c>@framerate</c>. Falls back to a