Revamp the architecture.

Currently:

1. OverloadedRecordUpdate is way less flexible, complete, and functional than lenses,
2. mtl-style typeclasses means we gotta use instances, I prefer the ergonomics and flexibility of Effects (handlers are mere functions),
3. There is no Card DSL,
4. There are tests, but we cannot deterministically inject randomness in a clean way. Currently, to test random functions, I have refactored a random foo function into a foo_handler function, where foo_handler generates the random numbers that are then passed as arguments into foo. For testing, I just need to specify the arguments for foo and test foo. However, this is not flexible. With mock effects, I can do this cleaner.