feat(dees-contextmenu,dees-appui-tabs,test): Prevent double-destruction of context menus, await window layer teardown, update destroyAll behavior, remove tabs content slot, and adjust tests

test/test.contextmenu-nested-close.browser.ts

@@ -76,8 +76,8 @@ tap.test('should close all parent menus when clicking action in nested submenu',
   expect(childItem).toBeTruthy();
   childItem!.click();
   
-  // Wait for menus to close
-  await new Promise(resolve => setTimeout(resolve, 200));
+  // Wait for menus to close (windowLayer destruction takes 300ms + context menu 100ms)
+  await new Promise(resolve => setTimeout(resolve, 600));
   
   // Verify action was called
   expect(actionCalled).toEqual(true);