Provide a basic account system with login and server side session store
identified by a cookie. Upon successful login a signed session cookie
is set by the server with the session stored on the server identifying
which account it is logged in as. The client uses a shared useFetch on
the session endpoint to identify if it's logged in and which account it
is logged in as, and refreshes this when loggin in or out.
If a span ended on midnight the next day header would be started on the
break and the sameDay check would match the day of the next span causing
the day header to be inserted into the break column. Fix by checking
that the last day header has a non-zero span in the same day check.
