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/api/departments.ts

@@ -0,0 +1,52 @@
+import { apiRequestData } from "./http";
+
+export type DepartmentItem = {
+  id: string;
+  name: string;
+  parentId: string | null;
+  archivedAt: string | null;
+  createdAt: string | null;
+  updatedAt: string | null;
+};
+
+export type DepartmentTreeNode = DepartmentItem & {
+  children: DepartmentTreeNode[];
+};
+
+export type DepartmentListResponse = {
+  includeArchived: boolean;
+  items: DepartmentItem[];
+  tree: DepartmentTreeNode[];
+};
+
+export async function fetchDepartments(params: { includeArchived?: boolean } = {}) {
+  const search = new URLSearchParams();
+  if (params.includeArchived != null) {
+    search.set("includeArchived", params.includeArchived ? "1" : "0");
+  }
+
+  const qs = search.toString();
+  return apiRequestData<DepartmentListResponse>(`/api/departments${qs ? `?${qs}` : ""}`);
+}
+
+export async function createDepartment(payload: { name: string; parentId?: string | null }) {
+  return apiRequestData<DepartmentItem>("/api/departments", {
+    method: "POST",
+    body: JSON.stringify(payload),
+  });
+}
+
+export async function updateDepartment(departmentId: string, payload: { name?: string; parentId?: string | null }) {
+  return apiRequestData<DepartmentItem>(`/api/departments/${departmentId}`, {
+    method: "PATCH",
+    body: JSON.stringify(payload),
+  });
+}
+
+export async function archiveDepartment(departmentId: string) {
+  return apiRequestData<DepartmentItem>(`/api/departments/${departmentId}/archive`, {
+    method: "POST",
+    body: JSON.stringify({}),
+  });
+}
+