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>

app/Http/Middleware/ActiveUserMiddleware.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+use Illuminate\Support\Facades\Auth;
+use Symfony\Component\HttpFoundation\Response;
+
+class ActiveUserMiddleware
+{
+    public function handle(Request $request, Closure $next): Response
+    {
+        if ($request->user() && (!$request->user()->is_active || $request->user()->trashed())) {
+            Auth::logout();
+            $request->session()->invalidate();
+            $request->session()->regenerateToken();
+
+            return redirect()->route('login')
+                ->with('error', __('auth_ui.account_deactivated'));
+        }
+
+        return $next($request);
+    }
+}