Before it was storing leaf data and Merkle roots, but nothing in between, since it wasn't yet interacting with intermediate layers (but it will once we hook up the FRI code).
As discussed, it seems like the batch opening argument will be a significant cost, and we can reduce that cost by not including shifted openings (except for `Z`s which need them).
I think this is the recommended way to apply Fiat-Shamir, to avoid any possible attacks like taking someone else's proof and using it to prove a slightly different statement.
Does this make sense? I think other libraries tend to include the leaf's index (either as an integer, or a series of bits indicating left/right turns) as part of a "proof". In FRI, the leaf indices are chosen by the verifier, so I thought that approach might be sort of redundant. Let me know what you think though.
