Finish countdown mode

[Oiroizoi]

I completed the front-end portion of this last year. The back end still needs to be done.

• Add a new mode called "countdown"
• /countdown should be a POST endpoint that accepts two form parameters: "minutes" and "seconds"
• Before starting a countdown, ensure the barmode is set to "countdown"
• When in countdown mode, the phrase box should show how much time is left
• The bar should also show the time remaining (For example, if the timer was set to 5:00 and one minute has passed, the Formbar should be 80% lit up)
• Play a sound effect when the countdown is done
• Once countdown mode is working, update the control panel: Replace this section

  if (document.getElementById("countdown").checked) {
   document.getElementById("playtime").checked = true;
   alert("This feature is not available yet.");
   //document.getElementById("countdownTime").classList.remove("hidden");
  }

  with this

  if (document.getElementById("countdown").checked) {
   request.open('GET', '/controlpanel?barmode=countdown');
   request.send();
   document.getElementById("countdownTime").classList.remove("hidden");
  }

[csmith1188]

Thanks!