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/nesbot/carbon/src/Carbon/Exceptions/UnknownGetterException.php

@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of the Carbon package.
+ *
+ * (c) Brian Nesbitt <brian@nesbot.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Carbon\Exceptions;
+
+use InvalidArgumentException as BaseInvalidArgumentException;
+use Throwable;
+
+class UnknownGetterException extends BaseInvalidArgumentException implements InvalidArgumentException
+{
+    /**
+     * The getter.
+     *
+     * @var string
+     */
+    protected $getter;
+
+    /**
+     * Constructor.
+     *
+     * @param string         $getter   getter name
+     * @param int            $code
+     * @param Throwable|null $previous
+     */
+    public function __construct($getter, $code = 0, ?Throwable $previous = null)
+    {
+        $this->getter = $getter;
+
+        parent::__construct("Unknown getter '$getter'", $code, $previous);
+    }
+
+    /**
+     * Get the getter.
+     *
+     * @return string
+     */
+    public function getGetter(): string
+    {
+        return $this->getter;
+    }
+}