feat: implement mail-login directadmin plugin

exec/lib/KeyName.php

@@ -0,0 +1,30 @@
+<?php
+declare(strict_types=1);
+
+final class KeyName
+{
+    public const MAX_LENGTH = 96;
+
+    public static function build(string $serverName, string $username, int $timestamp): string
+    {
+        $server = self::clean($serverName);
+        $user = self::clean($username);
+        $raw = 'autologin-' . $server . '-' . $user . '-' . $timestamp;
+        if (strlen($raw) <= self::MAX_LENGTH) {
+            return $raw;
+        }
+        $hash = substr(hash('sha256', $raw), 0, 10);
+        $suffix = '-' . $hash . '-' . $timestamp;
+        $bodyMax = self::MAX_LENGTH - strlen($suffix);
+        $body = rtrim(substr('autologin-' . $server . '-' . $user, 0, $bodyMax), '-');
+        return $body . $suffix;
+    }
+
+    private static function clean(string $value): string
+    {
+        $value = strtolower(trim($value));
+        $value = preg_replace('/[^a-z0-9-]+/', '-', $value) ?? '';
+        $value = trim($value, '-');
+        return $value !== '' ? $value : 'unknown';
+    }
+}