feat: integrate sha256 starky

[ratankaliani]

Overview

• test_skip_large and test_step_large pass with 128 validators.
  • test_step_large currently takes ~14.5 minutes to generate a proof.
  • test_skip_large currently takes ~15.5 minutes to generate a proof.
• Integrated Curta SHA-256 gadget into zkQGB.
• Fix Tried to route a wire that isn't routable issue (separate get_total_voting_power computation into 2 chunks, to avoid exceeding the max_num_routed_wires in the plonky2 config)

Future Optimizations

• Creating a SHA512 Curta gadget will speed up EDDSA signature verification, which is a significant remaining bottleneck.

Future Cleanup

• Currently it's necessary to compute the number of SHA's to fill out the 65K byte size of the Curta gadget. This leads to manual computation in skip and stephttps://github.com/succinctlabs/zkqgb/blob/5585abf6d067071fff00c86ff1722bd1bef2fd82/src/verify.rs#L290-L302
  • With a simplified interface in plonky2x for SHA256 that allocates the number of Curta gadget's necessary, this logic can be removed.
• To avoid unnecessary manual computation inside of tests, certain tests in validator.rs that call SHA256 have been commented out until a simplified interface for Curta's SHA256 in plonky2x is added https://github.com/succinctlabs/zkqgb/blob/5585abf6d067071fff00c86ff1722bd1bef2fd82/src/validator.rs#L915-L1241

[ratankaliani]

Updating these tests to use the Curta gadget felt unnecessary (given integration tests pass), will add them back once the Curta interface is more clean.