perf: add nested modal demo (#5353)

playground/src/views/examples/modal/nested-demo.vue

@@ -0,0 +1,24 @@
+<script lang="ts" setup>
+import { useVbenModal } from '@vben/common-ui';
+
+import { Button } from 'ant-design-vue';
+
+import DragDemo from './drag-demo.vue';
+
+const [Modal] = useVbenModal({
+  destroyOnClose: true,
+});
+const [BaseModal, baseModalApi] = useVbenModal({
+  connectedComponent: DragDemo,
+});
+
+function openNestedModal() {
+  baseModalApi.open();
+}
+</script>
+<template>
+  <Modal title="嵌套弹窗示例">
+    <Button @click="openNestedModal" type="primary">打开子弹窗</Button>
+    <BaseModal />
+  </Modal>
+</template>