feat: 采购申请新增库管'完结'功能(仿出库审批)

- 后端:approve 接口支持 action=close(已通过→已完结 status 1→4),模型 status_text 支持已完结
- 前端:采购申请状态tab加'已完结',已通过单显示'完结'按钮(库管)

inventory-backend/app/services/purchase_service.py

@@ -145,12 +145,22 @@ class PurchaseService:
         if not purchase:
             raise ValueError("采购申请不存在")
 
-        if purchase.status != 0:
-            raise ValueError("当前状态不允许审批")
-
         beijing_tz = timezone(timedelta(hours=8))
         now = datetime.now(beijing_tz)
 
+        # ★ 完结：库管将「已通过(1)」的申请单置为「已完结(4)」（仿出库审批）
+        if action == 'close':
+            if purchase.status != 1:
+                raise ValueError("仅「已通过」的采购申请可完结")
+            purchase.status = 4
+            purchase.approver_id = user_id
+            purchase.approved_at = now
+            db.session.commit()
+            return purchase
+
+        if purchase.status != 0:
+            raise ValueError("当前状态不允许审批")
+
         if action == 'approve':
             purchase.status = 1
             purchase.approver_id = user_id