chore: 初始化前端仓库并迁移 admin-ui

- 创建 rui-frontend 前端仓库
- 迁移 admin-ui 管理后台
- 创建 cashier-mobile 和 customer-mobile 占位项目
- 配置 pnpm workspace

admin-ui/src/components/CashierTablePage.vue

@@ -0,0 +1,66 @@
+<script setup lang="ts">
+import { ref } from 'vue'
+
+interface Props {
+  title: string
+  columns: any[]
+  loading?: boolean
+}
+
+const props = defineProps<Props>()
+const emit = defineEmits<{
+  (e: 'add'): void
+  (e: 'refresh'): void
+}>()
+
+const searchForm = ref({})
+</script>
+
+<template>
+  <div class="page-container">
+    <h2 class="text-xl font-bold mb-4">{{ title }}</h2>
+    
+    <div class="toolbar mb-4">
+      <el-button type="primary" @click="emit('add')">
+        新增
+      </el-button>
+      <el-button @click="emit('refresh')">
+        刷新
+      </el-button>
+    </div>
+
+    <el-table
+      v-loading="loading"
+      :data="[]"
+      stripe
+      border
+      style="width: 100%"
+    >
+      <el-table-column
+        v-for="col in columns"
+        :key="col.prop"
+        :prop="col.prop"
+        :label="col.label"
+        :width="col.width"
+        :min-width="col.minWidth"
+        :align="col.align || 'left'"
+      />
+      <el-table-column label="操作" width="180" align="center" fixed="right">
+        <template #default="{ row }">
+          <el-button link type="primary" size="small">编辑</el-button>
+          <el-button link type="danger" size="small">删除</el-button>
+        </template>
+      </el-table-column>
+    </el-table>
+  </div>
+</template>
+
+<style scoped>
+.page-container {
+  padding: 20px;
+}
+.toolbar {
+  display: flex;
+  gap: 8px;
+}
+</style>