feat: 支持取消指派打手，可重新指派他人

- 后台可取消进行中订单的指派：订单回未分配，冻结押金全额退还，记录事件与审计
- 工单列表新增「取消指派」按钮（带确认弹窗），客服/管理员/运营可用
- 取消后可重新指派给其他打手

apps/frontend/src/pages/admin/panels/WorkOrdersPanel.tsx

@@ -8,6 +8,7 @@ import {
   SearchOutlined,
   SendOutlined,
   TeamOutlined,
+  UndoOutlined,
   UserAddOutlined,
   WarningOutlined,
 } from '@ant-design/icons'
@@ -45,6 +46,7 @@ import {
   acceptAdminWorkOrder,
   assignAdminWorkOrderToWorker,
   createAdminMockWorkOrder,
+  unassignAdminWorkOrder,
   creditAdminWorkerWallet,
   deductAdminWorkOrderPendingDeposit,
   deleteAdminWorkCategory,
@@ -650,6 +652,35 @@ export default function WorkOrdersPanel() {
               指派
             </Button>
           ) : null}
+          {row.status === 'in_progress' && row.worker ? (
+            <Button
+              danger
+              icon={<UndoOutlined />}
+              onClick={() => {
+                const assignedWorker = row.worker
+                if (!assignedWorker) return
+                modal.confirm({
+                  title: '取消指派该打手？',
+                  content: (
+                    <span>
+                      将 {assignedWorker.displayName || assignedWorker.username} 的接单撤回，订单回到未分配，
+                      可重新指派给其他打手；冻结押金将退还。
+                    </span>
+                  ),
+                  okText: '确认取消指派',
+                  cancelText: '取消',
+                  okButtonProps: { danger: true },
+                  onOk: () =>
+                    runAction(
+                      () => unassignAdminWorkOrder(row.workOrderId),
+                      '已取消指派',
+                    ),
+                })
+              }}
+            >
+              取消指派
+            </Button>
+          ) : null}
           {row.status === 'pending_material' ? (
             <Button
               icon={<FormOutlined />}

apps/frontend/src/services/admin/worker-platform.ts

@@ -143,6 +143,12 @@ export function assignAdminWorkOrderToWorker(
   )
 }
 
+export function unassignAdminWorkOrder(workOrderId: number) {
+  return apiPost<{ order: WorkOrder }>(
+    `/api/v1/admin/worker-platform/orders/${workOrderId}/unassign`,
+  )
+}
+
 export function creditAdminWorkerWallet(
   workerId: number,
   payload: { amount: number; note?: string },