perf(booth): optimize assets and result flow

WebP reduces UI payload; JPEG keeps portrait saves compatible.\nFinish ends the visit without prompting another portrait.

components/screens/ConfirmScreen.tsx

@@ -27,7 +27,7 @@ export const ConfirmScreen: React.FC<ConfirmScreenProps> = ({
       <div className="w-full flex items-center justify-between px-1 mb-1 z-30 min-h-[40px]">
         <button
           onClick={onRetake}
-          className="p-2 px-3 rounded-2xl btn-cartoon-dark text-white flex items-center space-x-1 font-black text-xs cursor-pointer shadow-md"
+          className="p-2 px-3 rounded-2xl btn-cartoon-dark text-white flex items-center space-x-1 font-black text-sm cursor-pointer shadow-md"
         >
           <ArrowLeft size={16} className="stroke-[3]" />
           <span>{t(config.labels.retakeButton)}</span>
@@ -63,7 +63,7 @@ export const ConfirmScreen: React.FC<ConfirmScreenProps> = ({
       <div className="w-full max-w-sm flex items-center justify-center py-2 z-20 min-h-[70px]">
         <button
           onClick={onConfirm}
-          className="w-full max-w-[210px] sm:max-w-[240px] py-2 sm:py-2.5 px-4 game-btn-gold font-extrabold text-xs sm:text-sm tracking-wider flex items-center justify-center space-x-2 text-center select-none uppercase font-cinzel shadow-lg active:scale-95"
+          className="w-full max-w-[210px] sm:max-w-[240px] py-2 sm:py-2.5 px-4 game-btn-gold font-extrabold text-sm tracking-wider flex items-center justify-center space-x-2 text-center select-none uppercase font-cinzel shadow-lg active:scale-95"
         >
           <Check size={17} className="stroke-[3]" />
           <span>{t(config.labels.confirmButton)}</span>