Implement verify_merkle_proof for miden::agglayer

[Fumuran]

This PR implements a verify_merkle_proof helper procedure, which calculates the SMT root based on the provided Merkle Path and leaf, and compares it to the provided root to ensure they are equal.

TODO:

• Implement Solidity compatibility test

Closes: #2278

[mmagician]

The core of the logic looks very good

I haven't reviewed the test/test generation code yet

[mmagician]

Not for this PR, but I wonder if we should ensure that the caller in #2288 guarantees this

[Fumuran]

Excuse me for doing the force push, by mistake I rebased my local branch instead of merging it.

[Copilot]

Pull request overview

This PR wires up a full end-to-end SMT Merkle proof verification path for AggLayer, implementing verify_merkle_proof/calculate_root in MASM and validating them against Solidity’s DepositContractBase.verifyMerkleProof using shared test vectors. It also refactors shared Keccak/Merkle helpers and integrates the new verification into the bridge-in flow.

Changes:

• Implement crypto_utils::verify_merkle_proof and crypto_utils::calculate_root in MASM to compute SMT roots from Keccak-based Merkle paths and compare them against an expected root.
• Add Solidity and Rust test infrastructure (Foundry test, JSON vectors, Rust compatibility tests) to ensure Miden’s implementation matches the Solidity DepositContractBase behavior.
• Refactor shared Keccak/Merkle helper utilities (memory double-word load/store, test-only digest formatting) and integrate SMT root verification into bridge_in.masm with a dedicated error code.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
crates/miden-testing/tests/agglayer/test_utils.rs	Adds reusable keccak_digest_to_word_strings helper and updates mainnet_exit_root test constant used in AggLayer tests.
crates/miden-testing/tests/agglayer/mmr_frontier.rs	Refactors to reuse the shared keccak_digest_to_word_strings helper from test_utils instead of a local copy.
crates/miden-testing/tests/agglayer/crypto_utils.rs	Introduces JSON-based Merkle proof vectors, parsing logic, and a test_solidity_verify_merkle_proof_compatibility test that compiles and executes MASM scripts calling crypto_utils::verify_merkle_proof against Solidity-generated fixtures.
crates/miden-agglayer/src/errors/agglayer.rs	Adds ERR_SMT_ROOT_VERIFICATION_FAILED MASM error mapping for SMT root verification failures to Rust error definitions.
crates/miden-agglayer/solidity-compat/test/SMTMerkleProofVectors.t.sol	Adds a Foundry test contract that builds a canonical SMT over 32 leaves, generates leaves/roots/paths arrays, sanity-checks them via Solidity verifyMerkleProof, and serializes them to JSON.
crates/miden-agglayer/solidity-compat/test-vectors/merkle_proof_vectors.json	Commits the generated Merkle proof test vectors (leaves, roots, per-leaf Merkle paths) which are consumed by Rust tests for Miden–Solidity compatibility.
crates/miden-agglayer/asm/bridge/utils.masm	Introduces shared mem_store_double_word/mem_load_double_word helpers for double-word big-endian memory operations used by SMT/MMR code.
crates/miden-agglayer/asm/bridge/mmr_frontier32_keccak.masm	Refactors to use the new shared utils::mem_store_double_word/mem_load_double_word helpers instead of local copies.
crates/miden-agglayer/asm/bridge/crypto_utils.masm	Extends crypto utilities with type aliases, local layout constants, a fully-implemented verify_merkle_proof that computes the SMT root via calculate_root and compares to an expected root with word::eq, and a calculate_root loop that walks a 32-level Keccak Merkle path using mem_stream and index bits.
crates/miden-agglayer/asm/bridge/bridge_in.masm	Integrates SMT root verification into the bridge-in flow: adjusts MAINNET_EXIT_ROOT_PTR to point at the exit roots block, threads LEAF_VALUE through process_global_index_mainnet, calls crypto_utils::verify_merkle_proof, and asserts with ERR_SMT_ROOT_VERIFICATION_FAILED.
Makefile	Extends generate-solidity-test-vectors target to also run the new Foundry test that produces merkle_proof_vectors.json.

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[bobbinth]

Not a very in-depth review from me - but looks good! Thank you!