macos: initial window shouldn't support undo

macos/Sources/App/macOS/AppDelegate.swift

@@ -260,7 +260,9 @@ class AppDelegate: NSObject,
             //   - if we're opening a URL since `application(_:openFile:)` is called before this.
             //   - if we're restoring from persisted state
             if TerminalController.all.isEmpty && derivedConfig.initialWindow {
+                undoManager.disableUndoRegistration()
                 _ = TerminalController.newWindow(ghostty)
+                undoManager.enableUndoRegistration()
             }
         }
     }