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/var-dumper/Caster/CutArrayStub.php

@@ -0,0 +1,30 @@
+<?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\VarDumper\Caster;
+
+/**
+ * Represents a cut array.
+ *
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+class CutArrayStub extends CutStub
+{
+    public array $preservedSubset;
+
+    public function __construct(array $value, array $preservedKeys)
+    {
+        parent::__construct($value);
+
+        $this->preservedSubset = array_intersect_key($value, array_flip($preservedKeys));
+        $this->cut -= \count($this->preservedSubset);
+    }
+}