Refactor test utilities and enhance ASGI settings

- Cleaned up and standardized assertions in ApiTestMixin for API response validation.
- Updated ASGI settings to use os.environ for setting the DJANGO_SETTINGS_MODULE.
- Removed unused imports and improved formatting in settings.py.
- Refactored URL patterns in urls.py for better readability and organization.
- Enhanced view functions in views.py for consistency and clarity.
- Added .flake8 configuration for linting and style enforcement.
- Introduced type stubs for django-environ to improve type checking with Pylance.

core/mixins/__init__.py

@@ -1,9 +1,11 @@
 from django.views.generic.list import MultipleObjectMixin
 
+
 class HTMXFilterableMixin(MultipleObjectMixin):
     """
     A mixin that provides filtering capabilities for HTMX requests.
     """
+
     filter_class = None
 
     def get_queryset(self):
@@ -13,5 +15,5 @@ class HTMXFilterableMixin(MultipleObjectMixin):
 
     def get_context_data(self, **kwargs):
         context = super().get_context_data(**kwargs)
-        context['filter'] = self.filterset
-        return context
+        context["filter"] = self.filterset
+        return context