feat: Add Laravel tinker examples and update nominal accounts functionality

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

src/Exceptions/SignerException.php

@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Apoloz\AlfaBank\Exceptions;
+
+use RuntimeException;
+
+class SignerException extends RuntimeException
+{
+    //
+}