Prepare Kalendartool for MPM and disable invites

components/admin/UserManagement.tsx

@@ -6,6 +6,7 @@
  * Fehler werden inline angezeigt. Der eigene Account ist geschuetzt
  * (Server lehnt ab).
  */
+import { appFetch } from '@/lib/client-fetch';
 import { useCallback, useEffect, useState } from 'react';
 import { Button, Card, ErrorMessage, Badge } from '@/components/ui/ui';
 import { ModalShell } from '@/components/ui/ModalShell';
@@ -32,7 +33,7 @@ export function UserManagement({ currentUserId }: { currentUserId: string }) {
     setIsLoading(true);
     setError(null);
     try {
-      const response = await fetch('/api/users', { cache: 'no-store' });
+      const response = await appFetch('/api/users', { cache: 'no-store' });
       if (!response.ok) {
         const data = (await response.json().catch(() => null)) as
           | { error?: string }
@@ -65,7 +66,7 @@ export function UserManagement({ currentUserId }: { currentUserId: string }) {
     setPendingId(userId);
     setError(null);
     try {
-      const response = await fetch(`/api/users/${userId}`, {
+      const response = await appFetch(`/api/users/${userId}`, {
         method: 'PATCH',
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify({ role: nextRole }),