Stand: SMTP-Test, Admin-Mail-Tab, Notifiable-Fix, Lazy-Quill

- Fix: Notifiable-Trait zum User-Model hinzugefuegt (behebt notify()-500er)
- Installer: SMTP-Verbindungstest mit EsmtpTransport + Ueberspringen-Link
- Admin: Neuer E-Mail-Tab mit SMTP-Konfiguration + Verbindungstest
- Admin: Lazy Quill-Initialisierung (nur sichtbare Locale wird geladen)
- Uebersetzungen: 17 neue Mail-Keys in allen 6 Sprachen

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

vendor/symfony/http-foundation/Session/Storage/Handler/IdentityMarshaller.php

@@ -0,0 +1,36 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\HttpFoundation\Session\Storage\Handler;
+
+use Symfony\Component\Cache\Marshaller\MarshallerInterface;
+
+/**
+ * @author Ahmed TAILOULOUTE <ahmed.tailouloute@gmail.com>
+ */
+class IdentityMarshaller implements MarshallerInterface
+{
+    public function marshall(array $values, ?array &$failed): array
+    {
+        foreach ($values as $key => $value) {
+            if (!\is_string($value)) {
+                throw new \LogicException(\sprintf('%s accepts only string as data.', __METHOD__));
+            }
+        }
+
+        return $values;
+    }
+
+    public function unmarshall(string $value): string
+    {
+        return $value;
+    }
+}