refactor(annotation): 优化模板默认选择逻辑

- 添加 resolveTemplateTimestamp 函数解析模板时间戳
- 将默认模板选择逻辑从查找内置模板改为选择最新更新的模板
- 使用 reduce 方法实现按时间戳排序的模板选择
- 提高模板选择的准确性和时效性

frontend/src/pages/DataAnnotation/Create/CreateTask.tsx

@@ -34,8 +34,20 @@ const resolveTemplateDataType = (datasetType?: DatasetType) => {
       return undefined;
   }
 };
+const resolveTemplateTimestamp = (template: AnnotationTemplate) => {
+  const timestamp = template.updatedAt || template.createdAt;
+  const parsed = Date.parse(timestamp);
+  return Number.isNaN(parsed) ? 0 : parsed;
+};
 const resolveDefaultTemplate = (items: AnnotationTemplate[]) =>
-  items.find((template) => template.builtIn) || items[0];
+  items.reduce<AnnotationTemplate | undefined>((latest, current) => {
+    if (!latest) {
+      return current;
+    }
+    return resolveTemplateTimestamp(current) > resolveTemplateTimestamp(latest)
+      ? current
+      : latest;
+  }, undefined);
 
 export default function AnnotationTaskCreate() {
   const navigate = useNavigate();

frontend/src/pages/DataAnnotation/Create/components/CreateAnnotationTaskDialog.tsx

@@ -71,8 +71,20 @@ const resolveTemplateDataType = (datasetType?: DatasetType) => {
       return undefined;
   }
 };
+const resolveTemplateTimestamp = (template: AnnotationTemplate) => {
+  const timestamp = template.updatedAt || template.createdAt;
+  const parsed = Date.parse(timestamp);
+  return Number.isNaN(parsed) ? 0 : parsed;
+};
 const resolveDefaultTemplate = (items: AnnotationTemplate[]) =>
-  items.find((template) => template.builtIn) || items[0];
+  items.reduce<AnnotationTemplate | undefined>((latest, current) => {
+    if (!latest) {
+      return current;
+    }
+    return resolveTemplateTimestamp(current) > resolveTemplateTimestamp(latest)
+      ? current
+      : latest;
+  }, undefined);
 
 export default function CreateAnnotationTask({
   open,