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/Test/Constraint/ResponseHeaderSame.php

@@ -0,0 +1,45 @@
+<?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\Test\Constraint;
+
+use PHPUnit\Framework\Constraint\Constraint;
+use Symfony\Component\HttpFoundation\Response;
+
+final class ResponseHeaderSame extends Constraint
+{
+    public function __construct(
+        private string $headerName,
+        private string $expectedValue,
+    ) {
+    }
+
+    public function toString(): string
+    {
+        return \sprintf('has header "%s" with value "%s"', $this->headerName, $this->expectedValue);
+    }
+
+    /**
+     * @param Response $response
+     */
+    protected function matches($response): bool
+    {
+        return $this->expectedValue === $response->headers->get($this->headerName, null);
+    }
+
+    /**
+     * @param Response $response
+     */
+    protected function failureDescription($response): string
+    {
+        return 'the Response '.$this->toString();
+    }
+}