feat: add CatalogSale model with abstract base classes for Sale/SaleLine

- Introduced SaleAbstractModel and SaleLineAbstractModel as abstract bases
- Added CatalogSale and CatalogSaleLine models inheriting from them
- Created migration 0045 for new models
- Added CatalogSaleView, CatalogSaleSerializer with nested line creation
- Registered new models in admin
- Added catalog_sales router endpoint to URLs
- Removed placeholder api/ package (now redundant)

tienda_ilusion/don_confiao/models/sales.py

@@ -6,11 +6,31 @@ from django.core.exceptions import ValidationError
 from datetime import datetime
 
 
-class Sale(models.Model):
+class SaleAbstractModel(models.Model):
     customer = models.ForeignKey(Customer, on_delete=models.PROTECT)
     date = models.DateTimeField("Date")
     phone = models.CharField(max_length=13, null=True, blank=True)
     description = models.CharField(max_length=255, null=True, blank=True)
+
+    class Meta:
+        abstract = True
+
+
+class SaleLineAbstractModel(models.Model):
+    product = models.ForeignKey(
+        Product, null=False, blank=False, on_delete=models.CASCADE
+    )
+    quantity = models.DecimalField(
+        max_digits=10, decimal_places=2, null=True
+    )
+    unit_price = models.DecimalField(max_digits=9, decimal_places=2)
+    description = models.CharField(max_length=255, null=True, blank=True)
+
+    class Meta:
+        abstract = True
+
+
+class Sale(SaleAbstractModel):
     payment_method = models.CharField(
         max_length=30,
         choices=PaymentMethods.choices,
@@ -46,22 +66,31 @@ class Sale(models.Model):
         return sale_header_csv
 
 
-class SaleLine(models.Model):
+class SaleLine(SaleLineAbstractModel):
 
     sale = models.ForeignKey(Sale, on_delete=models.CASCADE)
-    product = models.ForeignKey(
-        Product, null=False, blank=False, on_delete=models.CASCADE
-    )
-    quantity = models.DecimalField(
-        max_digits=10, decimal_places=2, null=True
-    )
-    unit_price = models.DecimalField(max_digits=9, decimal_places=2)
-    description = models.CharField(max_length=255, null=True, blank=True)
 
     def __str__(self):
         return f"{self.sale} - {self.product}"
 
 
+class CatalogSale(SaleAbstractModel):
+
+    def __str__(self):
+        return f"{self.date} {self.customer}"
+
+    def get_total(self):
+        lines = self.catalogsaleline_set.all()
+        return sum([l.quantity * l.unit_price for l in lines])
+
+
+class CatalogSaleLine(SaleLineAbstractModel):
+    catalog_sale = models.ForeignKey(CatalogSale, on_delete=models.CASCADE)
+
+    def __str__(self):
+        return f"{self.catalog_sale} - {self.product}"
+
+
 class Payment(models.Model):
     date_time = models.DateTimeField()
     type_payment = models.CharField(