💄 style(verify-code): 调整 APP 端验证码输入框的隐藏方案

- 将原生输入框移出可视区域，避免 Android 设备上原生光标与自绘数字冲突
- 为 xt__verify-code 增加 overflow 隐藏，输入内容与光标不再显示在验证码格上

♻️ refactor(login): 移除 u-code 组件并自实现验证码倒计时

- 用 displayCodeTip 计算属性配合计时器替换 u-code，统一验证码按钮文案展示
- 新增 onBeforeUnmount 清理倒计时定时器，避免内存泄漏
- 重构 fetchCode 发送逻辑，简化校验与错误处理分支
- 更新获取验证码按钮样式为橙色渐变并调整文字颜色

♻️ refactor(live): 为 APP 端补充直播服务占位实现

- 通过条件编译在 APP-PLUS 下提供 LiveChatService 与 LiveMqttService 空实现
- 避免 APP 端引入直播聊天与 MQTT 依赖，仅保留其他平台原有逻辑

pages/promotion/live/room.vue

@@ -488,8 +488,34 @@ import {
 import config from '@/config/config'
 import { useStore } from '@/store'
 import { isLogin, navigateToLogin, unitPrice } from '@/utils/filters.js'
+// #ifndef APP-PLUS
 import { LiveChatService } from './utils/liveChat.js'
 import { LiveMqttService } from './utils/liveMqtt.js'
+// #endif
+// #ifdef APP-PLUS
+class LiveChatService {
+  userInfo: any = {}
+  constructor(_options: any = {}) {}
+  setGroupID(_id: string) {}
+  async initTencentIm(_viewLiveResult?: any) {}
+  cleanup() {}
+}
+class LiveMqttService {
+  userId: any = null
+  mqttClient: any = null
+  constructor(_liveId: any, userId: any) {
+    this.userId = userId
+  }
+  setMessageHandlers(_handlers: any) {}
+  isConnected() {
+    return false
+  }
+  initMqtt() {}
+  cleanup() {
+    this.mqttClient = null
+  }
+}
+// #endif
 import { findRecommendPayload, parseRecommendMessageArray } from './utils/liveRecommend.js'
 import { seedLiveSetting } from './utils/liveSetting.js'
 // #ifdef H5