🔧 Problem identified and fixed:
- nginx proxy was routing /api/groups to /groups (removing /api prefix)
- Backend route was registered under /api/groups instead of /groups
- Changed backend route registration from '/api/groups' to '/groups'
- Tested API endpoint: curl to /api/groups/qion_-lT1/reorder now works
- Removed debug console.log statements for cleaner production code
✅ Drag-and-drop reordering now functional in ModerationGroupImagesPage
✅ API requests properly routed through nginx proxy to backend
✅ Error 'Reihenfolge konnte nicht geändert werden' resolved
