Revert "remove deadcode"

This reverts commit 47f7524.

src/Internal/Exceptions/ExceptionInterface.php

@@ -31,4 +31,9 @@ interface ExceptionInterface extends Throwable
     public const TRANSACTION_FAILED = 1 << 10;
 
     public const MODEL_NOT_FOUND = 1 << 11;
+
+    /**
+     * @deprecated no longer used
+     */
+    public const TRANSACTION_START = 1 << 12;
 }

src/Internal/Exceptions/TransactionStartException.php

@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Bavix\Wallet\Internal\Exceptions;
+
+use LogicException;
+
+/**
+ * @deprecated no longer used
+ * @codeCoverageIgnore
+ */
+final class TransactionStartException extends LogicException implements LogicExceptionInterface
+{
+}