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/mailer/Transport/NullTransportFactory.php

@@ -0,0 +1,34 @@
+<?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\Mailer\Transport;
+
+use Symfony\Component\Mailer\Exception\UnsupportedSchemeException;
+
+/**
+ * @author Konstantin Myakshin <molodchick@gmail.com>
+ */
+final class NullTransportFactory extends AbstractTransportFactory
+{
+    public function create(Dsn $dsn): TransportInterface
+    {
+        if ('null' === $dsn->getScheme()) {
+            return new NullTransport($this->dispatcher, $this->logger);
+        }
+
+        throw new UnsupportedSchemeException($dsn, 'null', $this->getSupportedSchemes());
+    }
+
+    protected function getSupportedSchemes(): array
+    {
+        return ['null'];
+    }
+}