production runtime and mock removal

backend/internal/billing/ledger.go

@@ -51,6 +51,9 @@ func HTTPStatus(err error) int {
 	if errors.As(err, &status) {
 		return status.Status
 	}
+	if errors.Is(err, ErrProviderUnavailable) {
+		return 503
+	}
 	return 500
 }