Theme files are cached under a path that only changes with Keycloak's
version, for 30 days, so returning players kept the grey stylesheet.
It is renamed to login.css, and theme files are now cached for an hour.
The header is now the logo, the page's actions, how to play, settings
and the account. The theme swatches move into a settings menu; the
account shows the player's initials and is on every page through an
AuthUserContext. On phones the home page's actions leave the header for
a row of two buttons. Checked menu items get a check at their end.
