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/DependencyInjection/MergeExtensionConfigurationPass.php

@@ -0,0 +1,42 @@
+<?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\DependencyInjection;
+
+use Symfony\Component\DependencyInjection\Compiler\MergeExtensionConfigurationPass as BaseMergeExtensionConfigurationPass;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+
+/**
+ * Ensures certain extensions are always loaded.
+ *
+ * @author Kris Wallsmith <kris@symfony.com>
+ */
+class MergeExtensionConfigurationPass extends BaseMergeExtensionConfigurationPass
+{
+    /**
+     * @param string[] $extensions
+     */
+    public function __construct(
+        private array $extensions,
+    ) {
+    }
+
+    public function process(ContainerBuilder $container): void
+    {
+        foreach ($this->extensions as $extension) {
+            if (!\count($container->getExtensionConfig($extension))) {
+                $container->loadFromExtension($extension, []);
+            }
+        }
+
+        parent::process($container);
+    }
+}