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/deprecation-contracts/function.php

@@ -0,0 +1,27 @@
+<?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.
+ */
+
+if (!function_exists('trigger_deprecation')) {
+    /**
+     * Triggers a silenced deprecation notice.
+     *
+     * @param string $package The name of the Composer package that is triggering the deprecation
+     * @param string $version The version of the package that introduced the deprecation
+     * @param string $message The message of the deprecation
+     * @param mixed  ...$args Values to insert in the message using printf() formatting
+     *
+     * @author Nicolas Grekas <p@tchwork.com>
+     */
+    function trigger_deprecation(string $package, string $version, string $message, mixed ...$args): void
+    {
+        @trigger_error(($package || $version ? "Since $package $version: " : '').($args ? vsprintf($message, $args) : $message), \E_USER_DEPRECATED);
+    }
+}