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/admin.py

@@ -1,13 +1,21 @@
 from django.contrib import admin
 from .models.sales import Sale, SaleLine
 from .models.customers import Customer
-from .models.sales import Sale, SaleLine, Payment
+from .models.sales import (
+    Sale,
+    SaleLine,
+    CatalogSale,
+    CatalogSaleLine,
+    Payment,
+)
 from .models.products import Product, ProductCategory
 from .models.payments import ReconciliationJar
 
 admin.site.register(Customer)
 admin.site.register(Sale)
 admin.site.register(SaleLine)
+admin.site.register(CatalogSale)
+admin.site.register(CatalogSaleLine)
 admin.site.register(Product)
 admin.site.register(ProductCategory)
 admin.site.register(Payment)