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/translation/StaticMessage.php

@@ -0,0 +1,33 @@
+<?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\Translation;
+
+use Symfony\Contracts\Translation\TranslatableInterface;
+use Symfony\Contracts\Translation\TranslatorInterface;
+
+final class StaticMessage implements TranslatableInterface
+{
+    public function __construct(
+        private string $message,
+    ) {
+    }
+
+    public function getMessage(): string
+    {
+        return $this->message;
+    }
+
+    public function trans(TranslatorInterface $translator, ?string $locale = null): string
+    {
+        return $this->getMessage();
+    }
+}