Fix tenant event form package selector so it no longer renders empty-value options, handles loading/empty

states, and pulls data from the authenticated /api/v1/tenant/packages endpoint.
    (resources/js/admin/pages/EventFormPage.tsx, resources/js/admin/api.ts)
  - Harden tenant-admin auth flow: prevent PKCE state loss, scope out StrictMode double-processing, add SPA
    routes for /event-admin/login and /event-admin/logout, and tighten token/session clearing semantics (resources/js/admin/auth/{context,tokens}.tsx, resources/js/admin/pages/{AuthCallbackPage,LogoutPage}.tsx,
    resources/js/admin/router.tsx, routes/web.php)

resources/lang/de/emails.php

@@ -49,4 +49,11 @@ return [
         'subject' => 'Neue Kontakt-Anfrage',
         'body' => 'Kontakt-Anfrage von :name (:email): :message',
     ],
-];
+
+    'contact_confirmation' => [
+        'subject' => 'Vielen Dank für Ihre Nachricht, :name!',
+        'greeting' => 'Hallo :name,',
+        'body' => 'Vielen Dank für Ihre Nachricht an das Fotospiel-Team. Wir melden uns so schnell wie möglich zurück.',
+        'footer' => 'Viele Grüße<br>Ihr Fotospiel-Team',
+    ],
+];