Add key prop to CurrencySelector to force re-render on value change

Forces Preact to re-create the select element when currency changes,
ensuring the displayed value matches the controlled value prop.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: kitfunso

src/components/ui/calculator/CurrencySelector.tsx

@@ -81,6 +81,7 @@ export function CurrencySelector({ value, onChange, className = '' }: CurrencySe
 
   return (
     <select
+      key={`currency-select-${value}`}
       value={value}
       onChange={(e) => handleChange(e.currentTarget.value as Currency)}
       className={`