Prepare Kalendartool for MPM and disable invites

components/admin/EditCalendarForm.tsx

@@ -1,6 +1,7 @@
 'use client';
 
 /** Formular zum Bearbeiten/Deaktivieren eines Kalenders (Admin). */
+import { appFetch } from '@/lib/client-fetch';
 import { useState } from 'react';
 import { useRouter } from 'next/navigation';
 import { Button, Card, ErrorMessage, Input, Label } from '@/components/ui/ui';
@@ -29,7 +30,7 @@ export function EditCalendarForm({
 
     const formData = new FormData(event.currentTarget);
     try {
-      const response = await fetch(`/api/calendars/${calendarId}`, {
+      const response = await appFetch(`/api/calendars/${calendarId}`, {
         method: 'PATCH',
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify({