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-kernel/RebootableInterface.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\HttpKernel;
+
+/**
+ * Allows the Kernel to be rebooted using a temporary cache directory.
+ *
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+interface RebootableInterface
+{
+    /**
+     * Reboots a kernel.
+     *
+     * The getBuildDir() method of a rebootable kernel should not be called
+     * while building the container. Use the %kernel.build_dir% parameter instead.
+     *
+     * @param string|null $warmupDir pass null to reboot in the regular build directory
+     */
+    public function reboot(?string $warmupDir): void;
+}