Major refactor of commerce and Stripe integration

Refactored commerce models to support refunds, invoices, and improved carrier/payment logic. Added new serializers and viewsets for products, categories, images, discount codes, and refunds. Introduced Stripe client integration and removed legacy Stripe admin/model code. Updated Dockerfile for PDF generation dependencies. Removed obsolete migration files and updated configuration app initialization. Added invoice template and tasks for order cleanup.

backend/configuration/apps.py

@@ -1,6 +1,5 @@
 from django.apps import AppConfig
 from django.db.utils import OperationalError, ProgrammingError
-from .models import ShopConfiguration
 
 class ConfigurationConfig(AppConfig):
     default_auto_field = 'django.db.models.BigAutoField'
@@ -13,9 +12,11 @@ class ConfigurationConfig(AppConfig):
         makemigrations/migrate don't fail when the table does not yet exist.
         """
         try:
-            ShopConfiguration.get_solo()
+            from .models import ShopConfiguration  # local import to avoid premature app registry access
+            ShopConfiguration.get_solo()  # creates if missing
             
         except (OperationalError, ProgrammingError):
-            ShopConfiguration.objects.create()
+            # DB not ready (e.g., before initial migrate); ignore silently
+            pass