添加反向树加载功能，重构节点和树的选择逻辑

Co-authored-by: Copilot <copilot@github.com>

modeler/src/views/decision/designer/nodes-card.vue

@@ -72,8 +72,8 @@
 <script lang="ts">
 import { defineComponent, onMounted, ref } from 'vue';
 import type { NodeDragTemplate, NodeTemplate } from './template';
-import { findNodeTemplates } from './api';
 import { safePreventDefault, safeStopPropagation } from '@/utils/event';
+import { loadNodeTemplatesOnce } from './template-metadata-loader';
 
 export default defineComponent({
   emits: ['drag-item-start', 'drag-item-end'],
@@ -95,7 +95,7 @@ export default defineComponent({
       conditionTemplates.value = [];
       actionsTemplates.value = [];
 
-      findNodeTemplates().then(r => {
+      loadNodeTemplatesOnce().then(r => {
         templateData.value = r.data;
         if (r.data) {
           r.data.forEach(tpl => {