fix: exhaustive cleanup of usecases and compilation fixes

backend/internal/usecase/product_usecase.go

@@ -115,12 +115,6 @@ func (s *Service) SearchProducts(ctx context.Context, filter domain.ProductSearc
 		return nil, err
 	}
 
-	// Adjust displayed stock by subtracting reservations
-	// In production, the Repo query itself would handle this for better performance
-	// for i := range products {
-	// 	// This is a simplified adjustment. 
-	// }
-
 	return &domain.ProductSearchPage{Products: products, Total: total, Page: page, PageSize: pageSize}, nil
 }
 

backend/internal/usecase/usecase.go

@@ -154,4 +154,3 @@ func NewService(
 func (s *Service) GetNotificationService() notifications.NotificationService {
 	return s.notify
 }
-