quick quality of life update

quick quality-of-life update: you can change your username now.
usernames are not forever anymore
if you picked a username forever ago and have been stuck with it since, that is finally fixed. go to your profile settings, tap the edit button next to your username, pick the new one, and save.
after you change it, your account goes on a 30-day cooldown before you can change it again. the cooldown shows in settings so you know when your next change is available.
same username rules
usernames still need to be available, and they can only use letters, numbers, and underscores.
if the name is taken, blocked, or you are still inside the cooldown window, the app will tell you what happened instead of silently failing.
this is live on web and mobile. if youre on the app and do not see it yet, make sure you are on the latest version by completing quiting the app and reopening it.