Function keygen_halo2 

pub fn keygen_halo2(
    halo2_config: &Halo2Config,
    reader: &impl Halo2ParamsReader,
    shape: StaticVerifierShape,
    internal_recursive_vk: &MultiStarkVerifyingKey<SC>,
    root_vk: &MultiStarkVerifyingKey<RootSC>,
    dummy_root_proof: &Proof<RootSC>,
) -> Halo2ProvingKey

Generate a Halo2ProvingKey (static verifier + wrapper) by running a dummy root proof through the pipeline.

This is the self-contained keygen flow:

1. Build a [StaticVerifierProvingKey] from the root VK and proof shape
2. Generate a dummy snark from the static verifier
3. Build a [Halo2WrapperProvingKey] (auto-tuned or fixed k)
4. Return the composite Halo2ProvingKey