1. Accept the facility multiplier as a parameter instead of using $servantMilkersMultiplier.
2. Return a results object containing all the necessary information instead of using $milk, $milkSale, $cum, $cumSale, $fluid, and $fluidSale.  This also means we have an invariant return type between preview and execution modes, which things much easier from a type-safety perspective (i.e. we don't have to jump through as many hoops to make TS happy).
3. Merge logic between text and calculation.  Reduce the structural impact of preview mode; it's OK to generate and return text that we're not going to use.