docs(changelog): mark the multisig ECDSA change breaking

Author: 0xisk

CHANGELOG.md

@@ -13,7 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
-- Verify `ShieldedMultiSigV2` and `ShieldedMultiSigV3` approvals with the `secp256k1EcdsaVerify` standard-library primitive, removing `stubVerifySignature` from both presets. `execute` / `mint` / `burn` now take `Vector<2, Secp256k1Point>` public keys and `Vector<2, Secp256k1EcdsaSignature>` signatures, and signer commitments hash the public-key coordinates (`pkX`, `pkY`) instead of a `Bytes<64>` key. `ShieldedMultiSigV2`'s `execute` digest is now domain-separated and bound to the contract instance (`kernel.self()`) and the full recipient (kind and address). Both presets share the verification logic through the new `EcdsaSignerManager` module, which unifies the signer-commitment domain separator on `multisig:signer:`; `ShieldedMultiSigV2` previously used `MultiSig:signer:`, so its commitments change again. The module owns the instance salt and the signer registry, so `ShieldedMultiSigV3`'s `ledger()` reader no longer exposes `_instanceSalt`, and `ShieldedMultiSigV2` no longer exports the `VerificationState` and `SignerCommitmentInput` structs, which were part of its generated artifact types. These primitives require ZKIR v3, so `compile:multisig` now passes `--feature-zkir-v3`. (#826)
+- **Breaking:** Verify `ShieldedMultiSigV2` and `ShieldedMultiSigV3` approvals with `secp256k1EcdsaVerifyLowS` from the new `crypto/Ecdsa` module, removing `stubVerifySignature` from both presets. `execute` / `mint` / `burn` now take `Vector<2, Secp256k1Point>` public keys and `Vector<2, Secp256k1EcdsaSignature>` signatures, and signer commitments hash the public-key coordinates (`pkX`, `pkY`) instead of a `Bytes<64>` key. `ShieldedMultiSigV2`'s `execute` digest is now domain-separated and bound to the contract instance (`kernel.self()`) and the full recipient (kind and address). Both presets share the verification logic through the new `EcdsaSignerManager` module, which unifies the signer-commitment domain separator on `multisig:signer:`; `ShieldedMultiSigV2` previously used `MultiSig:signer:`, so its commitments change again. The module owns the instance salt and the signer registry, so `ShieldedMultiSigV3`'s `ledger()` reader no longer exposes `_instanceSalt`, and `ShieldedMultiSigV2` no longer exports the `VerificationState` and `SignerCommitmentInput` structs, which were part of its generated artifact types. These primitives require ZKIR v3, so `compile:multisig` now passes `--feature-zkir-v3`. (#826)
 - Upgrade the Compact toolchain and Midnight dependencies: compiler `0.31.0` → `0.34.0`, `@midnight-ntwrk/compact-runtime` `0.16.0` → `0.19.0`, `@midnight-ntwrk/ledger-v8` `8.1.0` → `@midnightntwrk/ledger-v9` `1.0.0-rc.3`, `@midnight-ntwrk/compact-js` `2.5.1` → `2.5.5-rc.8`, the `midnight-js` packages `4.1.1` → `5.0.0-beta.7`, and `@openzeppelin/compact-simulator` `^0.3.1` → `^0.4.0`. Contract `pragma language_version` raised `>= 0.23.0` → `>= 0.26.0` (the language version shipped with compiler 0.34.0). (#841)
 
 ## 0.3.0-alpha.2 (2026-08-11)