Enhance public access and error handling in site-related views and loaders

- Updated `DebugScopedRateThrottle` to allow public access for blueprint list requests with site filters.
- Modified `SiteViewSet` and `SiteBlueprintViewSet` to permit public read access for list requests.
- Enhanced `loadSiteDefinition` to resolve site slugs to IDs, improving the loading process for site definitions.
- Improved error handling in `SiteDefinitionView` and `loadSiteDefinition` for better user feedback.
- Adjusted CSS styles for better layout and alignment in shared components.

backend/igny8_core/modules/billing/views.py

@@ -81,8 +81,10 @@ class CreditBalanceViewSet(viewsets.ViewSet):
             'credits_remaining': credits_remaining,
         }
         
-        serializer = CreditBalanceSerializer(data)
-        return success_response(data=serializer.data, request=request)
+        # Validate and serialize data
+        serializer = CreditBalanceSerializer(data=data)
+        serializer.is_valid(raise_exception=True)
+        return success_response(data=serializer.validated_data, request=request)
 
 
 @extend_schema_view(