style(marketingEdit): 调整画布堆叠样式

- 添加 z-index 属性以确保元素正确显示层级

frontend/src/views/components/marketingEdit/index.vue

@@ -568,6 +568,7 @@ export default {
   background: rgba($primary1, 0.1);
   border-color: rgba($primary1, 0.3);
   color: $primary1;
+  z-index: 10;
 }
 
 .canvas-stack_body.active .canvas-stack_switch {