refactor: 移动端升级 Vue3 + uView Plus

将 lilishop-uniapp 从 Vue2/uView 1.6 迁移到 Vue3/uview-plus，优先支持 H5/微商城与微信小程序；移除 vendored uview-ui，改用 npm 依赖、Vuex4 与迁移脚本/补丁，并补充 VUE3_MIGRATION.md 回归清单。

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

pages/tabbar/home/template/tpl_flex_three.vue

@@ -2,7 +2,7 @@
 <template>
   <div class="layout">
     <u-image @click="modelNavigateTo(item)" height="240rpx" width="240rpx" class="image-mode" :src="item.img" v-for="(item, index) in res.list" :key="index">
-      <u-loading slot="loading"></u-loading>
+      <template #loading><u-loading></u-loading></template>
     </u-image>
   </div>
 </template>
@@ -33,7 +33,4 @@ export default {
   justify-content: center;
   background-size: cover;
 }
-img {
-  width: 111px;
-}
 </style>