Add statistic: Hours simulated

[lladdy]

With the aiarena.net micro ladder kicking off and introducing more significant variance into the daily match counts, there is a need for a more meaningful statistic to represent ladder performance at a quick glance.

Discord user savelas suggested we add "Hours simulated".

Not only might this be more meaningful for project maintainers and users, but it's also a more relatable figure for the general public.