Add JSDoc documentation and file headers to all source files

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/api/auth.js

@@ -1,10 +1,21 @@
+// The Lucia project.
+// Copyright 2023-2026 DSP, inc.  All rights reserved.
+// Authors:
+//   imacat.yang@dsp.im (imacat), 2023/9/23
+/** @module auth Authentication token refresh utilities. */
+
 import axios from 'axios';
 import { getCookie, setCookie, setCookieWithoutExpiration } from '@/utils/cookieUtil.js';
 
 /**
- * Refresh the access token using the refresh token cookie.
- * Uses plain axios (not apiClient) to avoid interceptor loops.
+ * Refreshes the access token using the stored refresh token cookie.
+ *
+ * Uses plain axios (not apiClient) to avoid interceptor loops. Updates
+ * both the access token (session cookie) and refresh token (6-month
+ * expiry) cookies.
+ *
  * @returns {Promise<string>} The new access token.
+ * @throws {Error} If the refresh request fails.
  */
 export async function refreshTokenAndGetNew() {
   const api = '/api/oauth/token';