refactor(manager): 优化全局空状态、错误图片占位并升级遗留消息语法

- 增加表格与树组件全局空状态 (el-empty) 样式规范
- 补齐视图图片语义化 alt，并添加全局图片加载异常 SVG 占位兜底
- 将砍价/秒杀/自定义面板中的 $Message 兼容语法替换为 ElMessage
- 清理冗余依赖 vuex，将 sass-loader 调整至 devDependencies

manager/src/views/member/list/index.vue

@@ -213,7 +213,7 @@
       <el-form ref="formRef" :model="form" :rules="ruleValidate" label-width="80px">
         <el-input v-model="form.id" style="display: none" />
         <el-form-item label="头像">
-          <img :src="form.face || defaultPic" class="face" />
+          <img alt="会员头像" :src="form.face || defaultPic" class="face" />
           <el-button
             type="primary"
             link

manager/src/views/member/list/memberRecycle.vue

@@ -98,7 +98,7 @@
     <el-dialog v-model="descFlag" :title="descTitle" width="500px" destroy-on-close>
       <el-form ref="formValidateRef" :model="formValidate" :rules="ruleValidate" label-width="80px">
         <el-form-item label="头像">
-          <img :src="formValidate.face" class="face" />
+          <img alt="会员头像" :src="formValidate.face" class="face" />
           <el-button
             type="primary"
             link