Add Silk middleware and related settings for performance monitoring

- Introduced SILK_ENABLED setting to toggle Silk middleware.
- Updated ALLOWED_HOSTS to include "testserver" when not in DEBUG mode.
- Modified urlpatterns to conditionally include Silk URLs.
- Added django-silk dependency to pyproject.toml.
- Enhanced feed queries to optimize performance and reduce N+1 issues.
- Updated tests to verify query limits for various feeds.

config/urls.py

@@ -11,10 +11,13 @@ if TYPE_CHECKING:
     from django.urls.resolvers import URLPattern
     from django.urls.resolvers import URLResolver
 
-urlpatterns: list[URLResolver] | list[URLPattern | URLResolver] = [  # type: ignore[assignment]
+urlpatterns: [URLPattern | URLResolver] = [  # type: ignore[assignment]
     path(route="", view=include("twitch.urls", namespace="twitch")),
 ]
 
+if getattr(settings, "ENABLE_SILK", False):
+    urlpatterns += [path("silk/", include("silk.urls", namespace="silk"))]
+
 # Serve media in development
 if settings.DEBUG:
     urlpatterns += static(