fix: return Chonk prove verification key

[AztecBot]

Summary

• return the serialized hiding-kernel VK from ChonkProve
• verify pinned Chonk flows and TS client proofs with the VK used by the proof, instead of recomputing it from hiding bytecode
• reuse the prove response VK for bb prove --write_vk

Root cause

The nightly debug failure was in ChonkPinnedIvcInputsTest.AllPinnedFlows, not in CMake compilation. ChonkProve generated a proof and verified it successfully with the accumulated hiding-kernel VK. The test then recomputed a VK through ChonkComputeVk from only the hiding-kernel bytecode. That write-VK/mock construction produced different hiding-kernel metadata (pub_inputs_offset 673 instead of 669, different selector commitments), so the verifier parsed the proof public inputs against the wrong VK and hit the debug databus assertion.

Verification

• cmake --preset debug -DAVM=OFF -DAVM_TRANSPILER_LIB=
• cmake --build --preset debug --target bbapi_tests -j 16
• cmake --build --preset debug --target bb -j 16
• build-debug/bin/bbapi_tests --gtest_filter='BBApiMsgpack/*.DefaultConstructorRoundtrip'
• build-debug/bin/bbapi_tests --gtest_filter='BBApiInputValidation.*:CBind.*'
• NATIVE_PRESET=debug CHONK_PINNED_IVC_FLOW='deploy_ecdsar1+sponsored_fpc' scripts/run_test.sh bbapi_tests ChonkPinnedIvcInputsTest.AllPinnedFlows
• corepack yarn prettier --check src/barretenberg/backend.ts

Notes: clang-format is not installed in this container. Full TS typecheck was blocked by missing ignored aztec-wsdb generated bindings, and ESLint was blocked by an unavailable eslint-plugin-import referenced by the repo config.

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Created by claudebox · group: slackbot