Figure out how hardcoded level-curves work

[RensDur]

In the frontend code, you'll find the file hardCoded.ts under src>lib>data. This file exports two constants that together make up the structure of the default model. It's not clear to me how these are structured, because the structure of the curve doesn't match the structure that's required by the current implementation.

The hardcoded model is currently implemented in structure [number, number][][], while the required structure reads number[][].

All updates that I've made to the code are located in branch impl-default-model.