refactor(service): enrich conversion client result

backend/internal/service/card_service.go

@@ -7,8 +7,17 @@ import (
 	"card-to-iban/internal/card"
 )
 
+type ConversionResult struct {
+	IBAN               string
+	UpstreamHTTPStatus int
+	RawResponse        []byte
+}
+
 type CardToIBANClient interface {
-	Convert(ctx context.Context, cardNumber string) (string, error)
+	Convert(
+		ctx context.Context,
+		cardNumber string,
+	) (ConversionResult, error)
 }
 
 type CardService struct {
@@ -24,15 +33,15 @@ func NewCardService(client CardToIBANClient) *CardService {
 func (s *CardService) ConvertCardToIBAN(
 	ctx context.Context,
 	cardNumber string,
-) (string, error) {
+) (ConversionResult, error) {
 	if err := card.Validate(cardNumber); err != nil {
-		return "", err
+		return ConversionResult{}, err
 	}
 
-	iban, err := s.client.Convert(ctx, cardNumber)
+	result, err := s.client.Convert(ctx, cardNumber)
 	if err != nil {
-		return "", fmt.Errorf("convert card to iban: %w", err)
+		return result, fmt.Errorf("convert card to iban: %w", err)
 	}
 
-	return iban, nil
+	return result, nil
 }