Add multiverifier folding to the recursive tree prover

[YairVaknin-starkware]

Replace the per-pair Cairo simple-bootloader run with a circuit-world fold: for each pair, build a circuit_multiverifier circuit that verifies both child circuit proofs, prove it, and make the resulting proof the parent for the next layer. The tree is balanced with odd-carry; there is no Cairo bootloader or wrapping step anymore.

The tree is homogeneous: the leaf cairo-verifier circuit and the multiverifier circuit are both padded to one shared TARGET_PADDING_SIZES, so they share a preprocessed-trace layout and a single SharedConfig verifies every layer (leaf proofs at layer 0, multiverifier proofs above).

Module layout:

• canonical: one-time CanonicalCircuit setup (circuit shape + shared config).
• fold: LayerEntry + reduce_pair (deserialize children, build/prove the multiverifier, reserialize the parent proof in memory).
• leaf_io: typed LeafInput manifest — inline output_values and preprocessed_root plus a path to a pure Proof<QM31>. Both are inline because neither is recoverable from the serialized proof; the per-leaf root also keeps the fold agnostic to the leaf's circuit type.
• output: root proof + flat output-values JSON + nested PackedNode tree.

Intermediate proofs are held in memory (no scratch dir). Drops the Cairo bootloader machinery and its resources/.

The circuit is TEMPORARILY configured to the privacy cairo-verifier fixture so the slow-tests e2e can fold a pre-generated leaf proof (duped 2/3/4x) without running leaf_prover; wiring in leaf_prover as the real leaf producer is the follow-up.

Type

• feature
• bugfix
• dev (no functional changes, no API changes)
• fmt (formatting, renaming)
• build
• docs
• testing

Description

Breaking changes?

• yes
• no

---

This change is 

[cursor]

PR Summary

High Risk
Changes which cryptographic crates back recursive proof folding and pins external git revisions for stwo/stwo-circuits—errors here break proof compatibility or verification correctness.

Overview
Dependency wiring for the recursive-tree binary’s circuit-world fold: the workspace pins stwo-circuits at ee9b130, adds workspace entries for circuits, circuit-verifier, circuit-multiverifier, and pulls stwo directly (5ea05973, parallel + prover) so folding matches what those circuits use. Cargo.lock picks up the new circuit-multiverifier package and minor transitive bumps.

stwo_run_and_prove_recursive_tree crate manifest drops the Cairo VM / bootloader stack (cairo-air, cairo-program-runner-lib, stwo-run-and-prove-common, etc.) and depends on the stwo-circuits prover/verifier/multiverifier stack plus leaf-proof-format and stwo. The slow-tests feature comment now describes an e2e multiverifier fold over a leaf fixture (with tracing-subscriber, tempfile, and host blake2 only in dev-deps for that test), not a Cairo bootloader run.

^{Reviewed by Cursor Bugbot for commit b7e0fd0. Bugbot is set up for automated code reviews on this repo. Configure here.}

[codecov]

Codecov Report

❌ Patch coverage is 98.21429% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.04%. Comparing base (fb876d7) to head (b7e0fd0).

Files with missing lines	Patch %	Lines
...ates/stwo_run_and_prove_recursive_tree/src/fold.rs	96.29%	3 Missing ⚠️
...stwo_run_and_prove_recursive_tree/src/canonical.rs	98.36%	1 Missing ⚠️

Additional details and impacted files

@@                 Coverage Diff                  @@
##           adar/leaf_prover     #381      +/-   ##
====================================================
- Coverage             65.62%   64.04%   -1.59%     
====================================================
  Files                    41       45       +4     
  Lines                  5775     5777       +2     
====================================================
- Hits                   3790     3700      -90     
- Misses                 1985     2077      +92     

Files with missing lines	Coverage Δ
...s/stwo_run_and_prove_recursive_tree/src/leaf_io.rs	100.00% <100.00%> (ø)
...rates/stwo_run_and_prove_recursive_tree/src/lib.rs	96.72% <100.00%> (+4.38%)	⬆️
...ates/stwo_run_and_prove_recursive_tree/src/main.rs	94.73% <100.00%> (-1.56%)	⬇️
...es/stwo_run_and_prove_recursive_tree/src/output.rs	100.00% <100.00%> (ø)
...stwo_run_and_prove_recursive_tree/src/canonical.rs	98.36% <98.36%> (ø)
...ates/stwo_run_and_prove_recursive_tree/src/fold.rs	96.29% <96.29%> (ø)

... and 7 files with indirect coverage changes

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[Gali-StarkWare]

You have all the leaf prover stuff here, rebase it on Adar's branch

@Gali-StarkWare partially reviewed 7 files and made 1 comment.
Reviewable status: 5 of 19 files reviewed, all discussions resolved (waiting on OmriEshhar1).