feat: 物品规则接单金额可填0并限制零元发布，客服增加发单指派权限

- 物品规则接单金额允许填 0（按数量计价不受影响）
- 接单金额为 0 的工单禁止发布：前端发布按钮置灰 + 后端 409 拦截
- 客服（support）获得发布工单与指派打手权限

apps/backend/src/services/worker-platform/admin-service.ts

@@ -247,11 +247,6 @@ export async function saveAdminWorkProductRule(payload: JsonObject = {}) {
         errorCode: 'work_product_rule_sharing_amount_invalid',
       })
     }
-  } else if (rewardAmount <= 0 && unitPriceFen <= 0) {
-    throw createHttpError('接单金额必须大于 0', {
-      statusCode: 400,
-      errorCode: 'work_product_rule_reward_invalid',
-    })
   }
   const finalRewardAmount = sharingEnabled ? resolvedSharingTotalAmount : rewardAmount
 
@@ -1001,6 +996,12 @@ export async function publishAdminWorkOrder(workOrderId: number | string) {
       errorCode: 'work_order_publish_status_invalid',
     })
   }
+  if (Number(workOrder.reward_amount || 0) <= 0) {
+    throw createHttpError('接单金额为 0，无法发布到大厅', {
+      statusCode: 409,
+      errorCode: 'work_order_publish_reward_invalid',
+    })
+  }
   const now = nowIso()
   const updated = await updateWorkOrder(workOrder.id, {
     status: WORK_ORDER_STATUS.OPEN,