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/translation/LocaleSwitcher.php

@@ -0,0 +1,83 @@
+<?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\Translation;
+
+use Symfony\Component\Routing\RequestContext;
+use Symfony\Contracts\Translation\LocaleAwareInterface;
+
+/**
+ * @author Kevin Bond <kevinbond@gmail.com>
+ */
+class LocaleSwitcher implements LocaleAwareInterface
+{
+    private string $defaultLocale;
+
+    /**
+     * @param LocaleAwareInterface[] $localeAwareServices
+     */
+    public function __construct(
+        private string $locale,
+        private iterable $localeAwareServices,
+        private ?RequestContext $requestContext = null,
+    ) {
+        $this->defaultLocale = $locale;
+    }
+
+    public function setLocale(string $locale): void
+    {
+        // Silently ignore if the intl extension is not loaded
+        try {
+            if (class_exists(\Locale::class, false)) {
+                \Locale::setDefault($locale);
+            }
+        } catch (\Exception) {
+        }
+
+        $this->locale = $locale;
+        $this->requestContext?->setParameter('_locale', $locale);
+
+        foreach ($this->localeAwareServices as $service) {
+            $service->setLocale($locale);
+        }
+    }
+
+    public function getLocale(): string
+    {
+        return $this->locale;
+    }
+
+    /**
+     * Switch to a new locale, execute a callback, then switch back to the original.
+     *
+     * @template T
+     *
+     * @param callable(string $locale):T $callback
+     *
+     * @return T
+     */
+    public function runWithLocale(string $locale, callable $callback): mixed
+    {
+        $original = $this->getLocale();
+        $this->setLocale($locale);
+
+        try {
+            return $callback($locale);
+        } finally {
+            $this->setLocale($original);
+        }
+    }
+
+    public function reset(): void
+    {
+        $this->setLocale($this->defaultLocale);
+    }
+}