chore(lint): fix lint errors seen when running npm run lint (#19844)

packages/core/src/agents/agentLoader.ts

@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import yaml from 'js-yaml';
+import { load } from 'js-yaml';
 import * as fs from 'node:fs/promises';
 import { type Dirent } from 'node:fs';
 import * as path from 'node:path';
@@ -262,7 +262,7 @@ export async function parseAgentMarkdown(
 
   let rawFrontmatter: unknown;
   try {
-    rawFrontmatter = yaml.load(frontmatterStr);
+    rawFrontmatter = load(frontmatterStr);
   } catch (error) {
     throw new AgentLoadError(
       filePath,