446b9b1388
Add household-wide currency preference for the budget section. Users can select from 13 currencies (EUR, USD, GBP, SEK, NOK, DKK, CHF, PLN, CZK, HUF, JPY, AUD, CAD) in Settings → Budget. - preferences API (GET/PUT) now includes currency field - budget page loads currency from preferences on render - formatAmount() uses locale-aware Intl.NumberFormat with chosen currency - settings page gains a Budget section with a currency select - all three locales (de, en, it) updated with new i18n keys