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/nikic/php-parser/lib/PhpParser/Internal/DiffElem.php

@@ -0,0 +1,31 @@
+<?php declare(strict_types=1);
+
+namespace PhpParser\Internal;
+
+/**
+ * @internal
+ */
+class DiffElem {
+    public const TYPE_KEEP = 0;
+    public const TYPE_REMOVE = 1;
+    public const TYPE_ADD = 2;
+    public const TYPE_REPLACE = 3;
+
+    /** @var int One of the TYPE_* constants */
+    public int $type;
+    /** @var mixed Is null for add operations */
+    public $old;
+    /** @var mixed Is null for remove operations */
+    public $new;
+
+    /**
+     * @param int $type One of the TYPE_* constants
+     * @param mixed $old Is null for add operations
+     * @param mixed $new Is null for remove operations
+     */
+    public function __construct(int $type, $old, $new) {
+        $this->type = $type;
+        $this->old = $old;
+        $this->new = $new;
+    }
+}