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/console/Output/BufferedOutput.php

@@ -0,0 +1,40 @@
+<?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\Console\Output;
+
+/**
+ * @author Jean-François Simon <contact@jfsimon.fr>
+ */
+class BufferedOutput extends Output
+{
+    private string $buffer = '';
+
+    /**
+     * Empties buffer and returns its content.
+     */
+    public function fetch(): string
+    {
+        $content = $this->buffer;
+        $this->buffer = '';
+
+        return $content;
+    }
+
+    protected function doWrite(string $message, bool $newline): void
+    {
+        $this->buffer .= $message;
+
+        if ($newline) {
+            $this->buffer .= \PHP_EOL;
+        }
+    }
+}