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/psy/psysh/src/EnvInterface.php

@@ -0,0 +1,25 @@
+<?php
+
+/*
+ * This file is part of Psy Shell.
+ *
+ * (c) 2012-2026 Justin Hileman
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Psy;
+
+/**
+ * Abstraction around environment variables.
+ */
+interface EnvInterface
+{
+    /**
+     * Get an environment variable by name.
+     *
+     * @return string|null
+     */
+    public function get(string $key);
+}