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/Session/Attribute/AttributeBagInterface.php

@@ -0,0 +1,53 @@
+<?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\Session\Attribute;
+
+use Symfony\Component\HttpFoundation\Session\SessionBagInterface;
+
+/**
+ * Attributes store.
+ *
+ * @author Drak <drak@zikula.org>
+ */
+interface AttributeBagInterface extends SessionBagInterface
+{
+    /**
+     * Checks if an attribute is defined.
+     */
+    public function has(string $name): bool;
+
+    /**
+     * Returns an attribute.
+     */
+    public function get(string $name, mixed $default = null): mixed;
+
+    /**
+     * Sets an attribute.
+     */
+    public function set(string $name, mixed $value): void;
+
+    /**
+     * Returns attributes.
+     *
+     * @return array<string, mixed>
+     */
+    public function all(): array;
+
+    public function replace(array $attributes): void;
+
+    /**
+     * Removes an attribute.
+     *
+     * @return mixed The removed value or null when it does not exist
+     */
+    public function remove(string $name): mixed;
+}