feat(telegram): exception carrying permanent/retry_after flags

includes/class-telegram-exception.php

@@ -0,0 +1,27 @@
+<?php
+declare(strict_types=1);
+
+namespace Cf7stg;
+
+final class TelegramException extends \Exception
+{
+    private bool $permanent;
+    private int $retry_after;
+
+    public function __construct(string $message, int $code = 0, bool $permanent = false, int $retry_after = 0)
+    {
+        parent::__construct($message, $code);
+        $this->permanent = $permanent;
+        $this->retry_after = max(0, $retry_after);
+    }
+
+    public function is_permanent(): bool
+    {
+        return $this->permanent;
+    }
+
+    public function retry_after(): int
+    {
+        return $this->retry_after;
+    }
+}