Cache leaderboard data (web)

[luttje]

Right now https://leaderboards.experiment.games/ performs a new query every time you view a page. This makes no sense, since the data is only updated once every day around midnight.

We should cache the data when it changes (so when the API is called around midnight). The view could fetch the data from that cache. We would use Laravel's Caching for this.

If anyone reading this is familiar with PHP/Laravel and thinking of contributing. This might be an accessible way to help out.

Thanks for considering.