feat: restore previous action on Escape from ActionSelect

Pressing Escape from ActionSelect now restores the previous action
(e.g. ActionClone) instead of staying in Select mode. Adds
ConnectEvents() to the Action base class for action resume support.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

OpenNest/Actions/Action.cs

@@ -15,6 +15,8 @@ namespace OpenNest.Actions
 
         public virtual void OnPlateChanged() { }
 
+        public virtual void ConnectEvents() { }
+
         public abstract void DisconnectEvents();
 
         public abstract void CancelAction();