- show drink price and Pfand separately on tiles and in cart
- add light/dark toggle on the bar-picker page (persisted)
- theme via CSS variables, applied on load for tablet + admin
- larger, bolder text throughout; much bigger total sum
- store created_at as UTC ISO; display/group in Europe/Berlin
- stats grouped by business day (sales night past midnight, 5am cutoff)
- add "Statistik zurücksetzen"
- allow deleting drinks/tresen (refused if referenced by sales)
- CSV exports local wall-clock time