fix: wait for AutoCAD command-queue readiness barrier

Plant3D2026/P_Rec_Annot/src/PRecAnnot.Plant3D2026/EntryPoint.cs

@@ -50,6 +50,12 @@ public sealed class EntryPoint : IExtensionApplication
     [CommandMethod("PHP_REC_AUTOMATION_START", CommandFlags.Session)]
     public void AutomationStartCommand() => FirstLimitedApplyAutomationBootstrap.Arm();
 
+    // Test-only command-queue barrier. It deliberately performs no Plant or
+    // drawing work; its CommandEnded event proves the activated document is
+    // ready before the coordinator calls the Plant APIs.
+    [CommandMethod("PHP_REC_AUTOMATION_READY")]
+    public void AutomationReadyCommand() { }
+
     private static void RunDiagnostic(string commandName)
     {
         var operationId = Guid.NewGuid().ToString("N");