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/ThrowableUtils.php

@@ -0,0 +1,37 @@
+<?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;
+
+use Symfony\Component\ErrorHandler\Exception\SilencedErrorContext;
+
+/**
+ * @internal
+ */
+class ThrowableUtils
+{
+    public static function getSeverity(SilencedErrorContext|\Throwable $throwable): int
+    {
+        if ($throwable instanceof \ErrorException || $throwable instanceof SilencedErrorContext) {
+            return $throwable->getSeverity();
+        }
+
+        if ($throwable instanceof \ParseError) {
+            return \E_PARSE;
+        }
+
+        if ($throwable instanceof \TypeError) {
+            return \E_RECOVERABLE_ERROR;
+        }
+
+        return \E_ERROR;
+    }
+}