fix(worker): 整单指派拼单订单无法验收

- 前端：拼单订单整单指派给本人时放行验收
- 后端：整单指派清掉 sharing_enabled；已有有效份额则拒绝

apps/backend/src/repositories/worker-platform/work-order-grab-repo.ts

@@ -143,6 +143,7 @@ export async function assignWorkOrderToWorker(input: {
   order: WorkOrderRow | null
   failureReason:
     | 'work_order_not_assignable'
+    | 'work_order_has_shares'
     | 'worker_active_order_limit'
     | 'worker_deposit_insufficient'
     | null
@@ -167,6 +168,19 @@ export async function assignWorkOrderToWorker(input: {
     }
     const fromStatus = workOrder.status
 
+    // 已有拼单份额的订单不能按整单指派：否则会出现“整单接单人 + 其他人的份额”混在一起。
+    const shareCountResult = await client.query<{ total: number }>(
+      `
+        SELECT COUNT(*)::int AS total
+        FROM work_order_shares
+        WHERE work_order_id = $1 AND status <> 'cancelled'
+      `,
+      [input.workOrderId],
+    )
+    if (Number(shareCountResult.rows[0]?.total || 0) > 0) {
+      return { order: null, failureReason: 'work_order_has_shares' }
+    }
+
     await ensureWorkerWalletWithClient(client, input.workerId, input.now)
     const wallet = await getWorkerWalletWithClient(client, input.workerId)
     const activeOrderCount = await countWorkerActiveOrdersWithClient(client, input.workerId)
@@ -193,6 +207,9 @@ export async function assignWorkOrderToWorker(input: {
           friend_added_at = NULL,
           gift_available_at = NULL,
           ${CLEAR_DELIVERY_RESIDUE_SQL},
+          -- 管理端/寄卖履约都是整单指派，不会创建 work_order_shares；
+          -- 必须同时清掉拼单标记，避免出现“已开拼单但没有份额”的脏状态。
+          sharing_enabled = false,
           updated_at = $2
         WHERE id = $4
       `,