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/process/Exception/ProcessStartFailedException.php

@@ -0,0 +1,43 @@
+<?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\Process\Exception;
+
+use Symfony\Component\Process\Process;
+
+/**
+ * Exception for processes failed during startup.
+ */
+class ProcessStartFailedException extends ProcessFailedException
+{
+    public function __construct(
+        private Process $process,
+        ?string $message,
+    ) {
+        if ($process->isStarted()) {
+            throw new InvalidArgumentException('Expected a process that failed during startup, but the given process was started successfully.');
+        }
+
+        $error = \sprintf('The command "%s" failed.'."\n\nWorking directory: %s\n\nError: %s",
+            $process->getCommandLine(),
+            $process->getWorkingDirectory(),
+            $message ?? 'unknown'
+        );
+
+        // Skip parent constructor
+        RuntimeException::__construct($error);
+    }
+
+    public function getProcess(): Process
+    {
+        return $this->process;
+    }
+}