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/Exception/SessionNotFoundException.php

@@ -0,0 +1,27 @@
+<?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\Exception;
+
+/**
+ * Raised when a session does not exist. This happens in the following cases:
+ * - the session is not enabled
+ * - attempt to read a session outside a request context (ie. cli script).
+ *
+ * @author Jérémy Derussé <jeremy@derusse.com>
+ */
+class SessionNotFoundException extends \LogicException implements RequestExceptionInterface
+{
+    public function __construct(string $message = 'There is currently no session available.', int $code = 0, ?\Throwable $previous = null)
+    {
+        parent::__construct($message, $code, $previous);
+    }
+}