在如下代码中新增一个验证码表单：<template> <div class="user-login login-bg"> <div class="user-login--content"> <!-- <img :src="logo" alt=""> --> <a-typography-title :level="3"> 新特能源还原炉群控平台 </a-typography-title> <a-form class="form mt-16" ref="formRef" :model="formState" :rules="rules" v-bind="layout"> <a-form-item class="form-item" has-feedback name="username"> <a-input class="input" v-model:value="formState.username" type="text" @keyup.enter="onSubmit()" placeholder="请输入用户名" autocomplete="off" allow-clear /> </a-form-item> <a-form-item class="form-item" has-feedback name="password"> <a-input class="input" v-model:value="formState.password" type="password" @keyup.enter="onSubmit()" placeholder="请输入登录密码" autocomplete="off" allow-clear /> </a-form-item> <a-button class="login-button mt-24" type="primary" size="large" block @click="onSubmit()">登录</a-button> </a-form> </div> <p class="records">@2021-2023 中科时代（北京）科技有限公司 版权所有 <a href="https://beian.miit.gov.cn/" target="_blank">京ICP备2021032638号-4</a></p> </div> </template>

可以在这段代码中新增一个验证码表单，如下所示：

<template>
  <div class="user-login login-bg">
    <div class="user-login--content">
      <!-- <img :src="logo" alt=""> -->
      <a-typography-title :level="3"> 新特能源还原炉群控平台 </a-typography-title>
      <a-form class="form mt-16" ref="formRef" :model="formState" :rules="rules" v-bind="layout">
        <a-form-item class="form-item" has-feedback name="username">
          <a-input class="input" v-model:value="formState.username" type="text" @keyup.enter="onSubmit()" placeholder="请输入用户名" autocomplete="off" allow-clear />
        </a-form-item>
        <a-form-item class="form-item" has-feedback name="password">
          <a-input class="input" v-model:value="formState.password" type="password" @keyup.enter="onSubmit()" placeholder="请输入登录密码" autocomplete="off" allow-clear />
        </a-form-item>
        <a-form-item class="form-item" has-feedback name="captcha">
          <a-input class="input" v-model:value="formState.captcha" type="text" @keyup.enter="onSubmit()" placeholder="请输入验证码" autocomplete="off" allow-clear />
        </a-form-item>
        <a-button class="login-button mt-24" type="primary" size="large" block @click="onSubmit()">登录</a-button>
      </a-form>
    </div>
    <p class="records">@2021-2023 中科时代（北京）科技有限公司 版权所有 <a href="https://beian.miit.gov.cn/" target="_blank">京ICP备2021032638号-4</a></p>
  </div>
</template>

在原有的代码基础上新增了一个表单项，其名称为 `captcha`，类型为文本框，用于输入验证码。可以根据实际情况修改其样式和验证规则。