fix(user): remove duplicate showLoginModal variable declaration

pwuniapp/pages/user/index.vue

@@ -336,8 +336,6 @@ const onRoleChanged = (role) => {
 
 // 登录/注册已全面重构升级为独立专属页面 /pages/auth/login
 // 保持向下兼容: switchDemoAccount, login-modal-mask, 一键授权快捷登录
-const showLoginModal = ref(false);
-
 const openLoginModal = () => {
   uni.navigateTo({
     url: '/pages/auth/login'