sfw185/BJJTimer ? reverse-engineered prompt

Build me a clean, mobile friendly Brazilian Jiu Jitsu round timer web app.

I want it to let me set round length and rest length with simple plus and minus buttons, then start, pause, and reset the session easily. It should show a big countdown, the current status like Get Ready, Round, or Rest, and the round number. Before the first round starts, add a short get ready countdown. During the last 10 seconds of a round, make the timer visually warn me, and play different sounds for ready, go, soon, and finish so I can use it on the mat without staring at the screen.

Please make it responsive for phone, tablet, and desktop, save the timer settings so they stick after refresh, and make it installable like a PWA so it works well on mobile. Keep the interface simple, bold, and easy to read in a gym setting.