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.

tests/e2e/conftest.py

@@ -23,9 +23,11 @@ def setup_page(page: Page):
     # Listen for console errors
     page.on(
         "console",
-        lambda msg: print(f"Browser console {msg.type}: {msg.text}")
-        if msg.type == "error"
-        else None,
+        lambda msg: (
+            print(f"Browser console {msg.type}: {msg.text}")
+            if msg.type == "error"
+            else None
+        ),
     )
 
     yield page