feat: 统一后端分页查询与前端服务层适配

后端新增通用分页模块，为报销单、员工、预算、agent 资产等
端点统一接入分页参数和游标查询，优化 repository 层分页实
现，前端服务层适配分页响应结构，完善预算图表和全局样式，
优化侧边栏和企业选择器组件，引入 Element Plus 插件注册。

web/src/main.js

@@ -1,12 +1,10 @@
 import { createApp } from 'vue'
 import { MotionPlugin } from '@vueuse/motion'
-import ElementPlus from 'element-plus'
-import zhCn from 'element-plus/es/locale/lang/zh-cn'
-import 'element-plus/dist/index.css'
 import App from './App.vue'
 import router from './router/index.js'
 import { installThemeSkin } from './composables/useThemeSkin.js'
 import { installSessionNavigation } from './composables/useSystemState.js'
+import './plugins/elementPlusStyles.js'
 import './assets/styles/element-plus-theme.css'
 import './assets/styles/detail-page-corners.css'
 import './assets/styles/components/enterprise-page-shell.css'
@@ -18,6 +16,5 @@ installSessionNavigation(router)
 
 app.use(MotionPlugin)
 app.use(router)
-app.use(ElementPlus, { locale: zhCn })
 
 app.mount('#app')