feature: round/turn 'countdown timers' for initiative stack

[rsek]

format as a button. displays remaining rounds/turns til it expires. on expiry, fire an alert that's included with the token draw output.

• add with a button, probably: "Set Timer". filling the last
• probably needs an ephemeral prompt to handle configuration of the timer. set 1-25 rounds/turns? alternately: click dropdown/button to to increment by amount (+1, +5, +10, -1, -5, -10)?
• user-supplied label for button via modal?
• clicking the button prompts user w/ ephemeral to confirm removal of timer