- Add new 'invoice-items-muh' element to invoice template
- Add 'Positionen' category back to palette groups
- Create helper functions to format price and generate invoice content
- Add /current endpoint to SystemPricingController for authenticated users
- Load pricing when creating starter layout and display:
- Monatliche Systemgebühr MUH with net price
- Umsatzsteuer (19%)
- Gesamtsumme (brutto)
- Update starter layout positioning for new element