feat: 新增数字员工管理页面与工作台首页重构

后端优化 agent 资产种子初始化和常量配置，前端新增数字员工
视图和调度对话框组件，重构个人工作台首页布局和洞察面板，
完善审计页面数字员工详情和运行时模型，优化侧边栏导航和图
标配置，新增工作台摘要和工作台数据模块，补充单元测试。

web/src/assets/styles/app.css

@@ -135,6 +135,7 @@
 .main.archive-main,
 .main.policies-main,
 .main.audit-main,
+.main.digital-employees-main,
 .main.logs-main,
 .main.employees-main,
 .main.settings-main {
@@ -151,10 +152,12 @@
 .workarea { min-height: 0; overflow: auto; padding: 24px; }
 .workarea.requests-workarea,
 .workarea.documents-workarea,
+.workarea.workbench-workarea,
 .workarea.approval-workarea,
 .workarea.archive-workarea,
 .workarea.policies-workarea,
 .workarea.audit-workarea,
+.workarea.digital-employees-workarea,
 .workarea.logs-workarea,
 .workarea.employees-workarea,
 .workarea.settings-workarea {
@@ -162,6 +165,10 @@
   overflow: hidden;
   padding: 20px 24px;
 }
+.workarea.workbench-workarea {
+  overflow: hidden;
+  padding: 12px 14px 14px;
+}
 .workarea.settings-workarea {
   padding: 0;
   background: #fff;
@@ -195,6 +202,7 @@
   }
 
   .workarea { padding: 18px 16px 28px; }
+  .workarea.workbench-workarea { overflow: auto; padding: 14px; }
 }
 
 @media (prefers-reduced-motion: reduce) {