silent server-side users/characters.

no visible changes to players. on the backend, everyone gets a server-side user account and character, and the game writes to the server with every action.

server data isn't yet used for anything - anything read from the server should be mostly ignored. the client-side savestate is still the authority. server stuff won't be visible to players until 1.1.

doing all this silently/invisibly lets us solve scaling problems before they impact players.