Configures CngxNumericInput to format its value with a currency's grouping
and standard fraction digits (USD -> 2, JPY -> 0) - the currency code
drives the number; the symbol is never baked into the editable value. Render
the symbol with a CngxPrefix / CngxSuffix affix instead, so a screen
reader hears the field label rather than "dollar sign" and the editable text
stays a plain number (Pillar 3: configuration over a new organism).