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/polyfill-php80/Resources/stubs/Attribute.php

@@ -0,0 +1,31 @@
+<?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.
+ */
+
+#[Attribute(Attribute::TARGET_CLASS)]
+final class Attribute
+{
+    public const TARGET_CLASS = 1;
+    public const TARGET_FUNCTION = 2;
+    public const TARGET_METHOD = 4;
+    public const TARGET_PROPERTY = 8;
+    public const TARGET_CLASS_CONSTANT = 16;
+    public const TARGET_PARAMETER = 32;
+    public const TARGET_ALL = 63;
+    public const IS_REPEATABLE = 64;
+
+    /** @var int */
+    public $flags;
+
+    public function __construct(int $flags = self::TARGET_ALL)
+    {
+        $this->flags = $flags;
+    }
+}