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/error-handler/Debug.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\ErrorHandler;
+
+/**
+ * Registers all the debug tools.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class Debug
+{
+    public static function enable(): ErrorHandler
+    {
+        error_reporting(\E_ALL & ~\E_DEPRECATED & ~\E_USER_DEPRECATED);
+
+        if (!\in_array(\PHP_SAPI, ['cli', 'phpdbg', 'embed'], true)) {
+            ini_set('display_errors', 0);
+        } elseif (!filter_var(\ini_get('log_errors'), \FILTER_VALIDATE_BOOL) || \ini_get('error_log')) {
+            // CLI - display errors only if they're not already logged to STDERR
+            ini_set('display_errors', 1);
+        }
+
+        @ini_set('zend.assertions', 1);
+        ini_set('assert.active', 1);
+        ini_set('assert.exception', 1);
+
+        DebugClassLoader::enable();
+
+        return ErrorHandler::register(new ErrorHandler(new BufferingLogger(), true));
+    }
+}