starknet_transaction_prover,workspace: run the circuit verifier as a bootloader task

[einat-starkware]

Part 4 of the single-proof verification stack. This PR closes milestone 1: a single transaction's proof is verified by the real Cairo1 circuit verifier running as a bootloader task, and the verifier's output digest is checked against the digest recomputed from the transaction's proof facts. No OS program changes.

• run_circuit_verifier_task: runs the privacy circuit verifier executable as a single simple-bootloader task on the transaction's processed proof and parses the bootloader's output page ([1, 10, verifier_program_hash, digest words 0..7]).
• verify_circuit_verifier_task_output: checks the verifier program hash against a pinned value, then compares the verifier's output digest with compute_verification_digest of the given processed-proof output digest.
• Fixture: the proving side's processing of the golden leaf, generated with stwo_run_and_prove_recursive_tree at proving commit b75d21f9 under the canonical_small registry. The end-to-end test passes: bootloader-run verifier digest == digest recomputed from the transaction's proof facts. Invalid-proof, wrong-program-hash and wrong-digest paths are covered.

Reading the digest from the OS output (the packed low/high felts and unpack_output_digest) moved to #15064.

Stack (restructured):

• Milestone 1: apollo_starknet_os_program,starknet_os: add the Cairo0 processed-proof digests #15092 ← apollo_starknet_os_program,starknet_os: cite the circuit hashes' source and add todos #15086 ← this PR ← starknet_os_flow_tests,starknet_os,starknet_transaction_prover: test the Cairo digest via verifier #15095
• Milestone 2, the digest in the OS output: ← apollo_starknet_os_program,starknet_os,blockifier: emit the single-proof digest in the OS output #15064

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https://claude.ai/code/session_01E43QxCycT6DpDJo435Ft8R

[reviewable-StarkWare]

This change is 

[cursor]

PR Summary

Medium Risk
Introduces proof-verification logic tied to pinned verifier binaries and digest semantics; dependency split between cairo-program-runner-lib 1.3.1 and 2.4.0 increases integration risk, but changes are isolated to the transaction prover with strong test coverage.

Overview
Adds a new verifier_task module to starknet_transaction_prover that runs the Stwo circuit verifier executable as a single simple-bootloader Cairo task (via cairo-program-runner-lib) over a transaction’s processed proof, then validates the result.

run_circuit_verifier_task stages the verifier executable and processed proof on disk, builds a Cairo1 program task, runs the simple bootloader with all_cairo_stwo layout, and parses the bootloader output page into CircuitVerifierTaskOutput (pinned verifier program hash + Blake2s verification digest). verify_circuit_verifier_task_output checks the hash against an expected felt and compares the digest to compute_verification_digest from the proof’s output digest (from starknet_os::proof_fact_fold).

The crate gains a direct cairo-program-runner-lib dependency; Cargo.lock resolves 1.3.1 for this crate while proving-stack crates stay on 2.4.0, and several proving dependencies move to hashbrown 0.17.1. Tests use gzipped fixtures and cover happy path, wrong hash/digest, and corrupted proof failure.

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[einat-starkware]

Closing: the stack now runs the circuit verifier in Cairo, from the aggregator (#15161, #15163, #15162), instead of as a Rust bootloader task. This PR's verifier and processed-proof fixtures moved to starknet_os in #15163.

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