recall rate caching

this ones a bit tricky cause it changes all the time lol

i could on each card calculate the recall rate at many points forward like 10 days 50 days 100 days then cache that and intrapolate it

it should also contain the hash of all the history recall of the dependents and dependencies since those affect it so if a dependent has changed we invalidate the cache perhaps?

actually, let's not do anything until we know it's actually a bottle neck perhaps it's very fast actually since it's in memory