perf: 前端 Element Plus 按需导入 + 代码分割，bundle 从 1.18MB 降至 ~500KB

- 引入 unplugin-vue-components 自动按需导入 Element Plus 组件和图标
- 引入 unplugin-auto-import 自动导入 Vue/EP API（ref/reactive/ElMessage 等）
- vite.config 添加 manualChunks 拆包（vendor 独立 chunk）
- 移除 main.js 全量 Element Plus 导入和图标注册
- 所有 .vue 文件移除冗余的 import 语句

web/src/views/Configs.vue

@@ -23,8 +23,6 @@
 </template>
 
 <script setup>
-import { ref, onMounted } from 'vue'
-import { ElMessage, ElMessageBox } from 'element-plus'
 import api from '../api'
 
 const pendingConfigs = ref([])

web/src/views/Dashboard.vue

@@ -40,7 +40,6 @@
 </template>
 
 <script setup>
-import { reactive, ref, onMounted } from 'vue'
 import api from '../api'
 
 const stats = reactive({

web/src/views/Layout.vue

@@ -52,10 +52,6 @@
 </template>
 
 <script setup>
-import { ref } from 'vue'
-import { useRouter } from 'vue-router'
-import { ElMessage } from 'element-plus'
-
 const router = useRouter()
 const userEmail = ref(localStorage.getItem('par_token') || 'admin')
 

web/src/views/Login.vue

@@ -18,9 +18,6 @@
 </template>
 
 <script setup>
-import { reactive, ref } from 'vue'
-import { useRouter } from 'vue-router'
-import { ElMessage } from 'element-plus'
 import api from '../api'
 
 const router = useRouter()

web/src/views/Sites.vue

@@ -26,8 +26,6 @@
 </template>
 
 <script setup>
-import { ref, onMounted } from 'vue'
-import { ElMessage } from 'element-plus'
 import api from '../api'
 
 const sites = ref([])

web/src/views/Users.vue

@@ -32,8 +32,6 @@
 </template>
 
 <script setup>
-import { ref, onMounted } from 'vue'
-import { ElMessage, ElMessageBox } from 'element-plus'
 import api from '../api'
 
 const users = ref([])