Fix NameError: import services registry in create_app scope

The services singleton was used in before_request closures but the
import was removed when refactoring to domain_services_fn.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app.py

@@ -82,6 +82,7 @@ async def cart_context() -> dict:
 
 def create_app() -> "Quart":
     from shared.models.page_config import PageConfig
+    from shared.services.registry import services
     from services import register_domain_services
 
     app = create_base_app(