fix: added merchant_id to printing_order and plate_order

printing/models.py

@@ -11,6 +11,17 @@ from stateflow import models as stateflow_models
 class PlateOrder(ModelBase):
     """开版管理订单"""
     
+    # 商户关联（多租户）
+    merchant = models.ForeignKey(
+        basic_models.Merchant,
+        on_delete=models.PROTECT,
+        null=True,
+        blank=True,
+        related_name='plate_orders',
+        verbose_name='商户',
+        help_text='所属商户，可空以兼容历史数据'
+    )
+    
     # 自动编号相关
     design_code = models.CharField(max_length=50, blank=True, null=True, verbose_name='设计编号')
     original_id = models.PositiveBigIntegerField(
@@ -245,6 +256,18 @@ class PlateOrder(ModelBase):
 
 class PrintingOrder(ModelBase):
     """PrintingOrder model representing a printing order."""
+    
+    # 商户关联（多租户）
+    merchant = models.ForeignKey(
+        basic_models.Merchant,
+        on_delete=models.PROTECT,
+        null=True,
+        blank=True,
+        related_name='printing_orders',
+        verbose_name='商户',
+        help_text='所属商户，可空以兼容历史数据'
+    )
+    
     customer = models.ForeignKey(
         basic_models.Customer, 
         on_delete=models.PROTECT, 
@@ -327,6 +350,18 @@ class PrintingJobWorkStateEnum(models.IntegerChoices):
 
 class PrintingJob(ModelBase):
     """PrintingJob model representing a printing job associated with an order."""
+    
+    # 商户关联（多租户）
+    merchant = models.ForeignKey(
+        basic_models.Merchant,
+        on_delete=models.PROTECT,
+        null=True,
+        blank=True,
+        related_name='printing_jobs',
+        verbose_name='商户',
+        help_text='所属商户，可空以兼容历史数据'
+    )
+    
     printing_order = models.ForeignKey(
         PrintingOrder, 
         on_delete=models.CASCADE,