feat: add printing_job field to SalesOrderItem model for associating with printing tasks

business/models.py

@@ -278,6 +278,14 @@ class SalesOrderItem(ModelBase):
         related_name='sales_order_items',
         verbose_name='产品',
     )
+    printing_job = models.ForeignKey(
+        'printing.PrintingJob',
+        on_delete=models.SET_NULL,
+        related_name='sales_order_items',
+        null=True,
+        blank=True,
+        verbose_name='关联印染任务',
+    )
     price = models.DecimalField(max_digits=15, decimal_places=2, verbose_name='单价')
     color = models.CharField(max_length=50, null=True, blank=True, verbose_name='颜色')
     quantity = models.DecimalField(max_digits=10, decimal_places=2, verbose_name='数量')