fix: login page now shows error message on wrong password

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/api/index.js

@@ -24,7 +24,9 @@ api.interceptors.response.use(
     if (err.response?.status === 401) {
       const isOnLogin = window.location.pathname === '/login'
       localStorage.removeItem('token')
-      if (!isOnLogin) {
+      if (isOnLogin) {
+        ElMessage.error(msg || '用户名或密码错误')
+      } else {
         router.push('/login')
         ElMessage.error('登录已过期，请重新登录')
       }