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/KioskFrame.tsx

@@ -111,7 +111,7 @@ export const KioskFrame: React.FC<KioskFrameProps> = ({
           href="https://www.shanghaikarate.com"
           target="_blank"
           rel="noopener noreferrer"
-          className="text-[8.5px] sm:text-[9.5px] text-white/50 hover:text-amber-300 transition-colors whitespace-nowrap overflow-hidden text-ellipsis tracking-wide"
+          className="kiosk-footer-label text-[10px] sm:text-[11px] text-white/70 hover:text-amber-300 transition-colors whitespace-nowrap overflow-hidden text-ellipsis tracking-wide"
           title="Shanghai Karate Club (shanghaikarate.com)"
         >
           <span>上海健志空手道馆 · Shanghai Karate Club · Est. 2008</span>