Create a short one-shot tutorial / onboarding flow for first-time users

ask for a language preference -- save that globally for the app

teach the gestures

teach that the app keeps running and notifying when closed (we will make it true later, it's broken now)

encourage user briefly to get creative with the app using the settings (use it to time their turns during a chess match, to do apnoea training incrementally, to do pomodoro, etc.). but keep it short, respect their time (and ours -- we need to maintain translations for all this, you know)

save in local storage a boolean to tell the app whether they've done the tutorial already

make sure we're able to publish new versions of the tutorial though, so don't just call the boolean has_completed_tutorial

make it skippable

make it replayable by clicking an icon in settings (ic_menu_help)

start the app paused