feat(client): 部门管理与员工创建增强(F32)

- 新增部门管理页：列表/创建/归档
- 用户创建支持选择部门与直属上级
- 补齐 departments/employees API 封装与导航入口

client/src/router/index.tsx

@@ -4,6 +4,7 @@ import { AuthLayout } from "../layouts/AuthLayout";
 import { AuditLogsPage } from "../pages/AuditLogsPage";
 import { ChangePasswordPage } from "../pages/ChangePasswordPage";
 import { DashboardPage } from "../pages/DashboardPage";
+import { DepartmentsPage } from "../pages/DepartmentsPage";
 import { DelegationsPage } from "../pages/DelegationsPage";
 import { ForbiddenPage } from "../pages/ForbiddenPage";
 import { InvoicePoolPage } from "../pages/InvoicePoolPage";
@@ -128,6 +129,15 @@ export function AppRouter() {
           }
         />
 
+        <Route
+          path="system/departments"
+          element={
+            <RequirePermission anyOf={["system.users"]}>
+              <DepartmentsPage />
+            </RequirePermission>
+          }
+        />
+
         <Route path="settings/profile" element={<ProfilePage />} />
       </Route>