feat(wasm-utxo): add MuSig2 external crate implementation

Add k256-based MuSig2 crate to implement BIP327 key aggregation. This
allows us to use a standard implementation while maintaining our own
legacy algorithms for backward compatibility.

Includes test cases to verify that external crate produces identical
results to our internal implementation.

Issue: BTC-2652

Co-authored-by: llm-git <[email protected]>

Author: OttoAllmendinger

packages/wasm-utxo/Cargo.lock

@@ -18,6 +18,8 @@ wasm-bindgen = "0.2"
 js-sys = "0.3"
 miniscript = { git = "https://github.com/BitGo/rust-miniscript", tag = "miniscript-12.3.4-opdrop" }
 bech32 = "0.11"
+musig2 = { version = "0.3.1", default-features = false, features = ["k256"] }
+getrandom = { version = "0.2", features = ["js"] }
 
 [dev-dependencies]
 base64 = "0.22.1"

packages/wasm-utxo/Cargo.toml

@@ -10,7 +10,7 @@ allow-git = ["https://github.com/BitGo/rust-miniscript"]
 
 # Allow common licenses used in the Rust ecosystem
 [licenses]
-allow = ["MIT", "Apache-2.0", "CC0-1.0", "MITNFA", "Unicode-DFS-2016"]
+allow = ["MIT", "Apache-2.0", "CC0-1.0", "MITNFA", "Unicode-DFS-2016", "BSD-3-Clause", "Unlicense"]
 # Clarify license for unlicensed crate
 [[licenses.clarify]]
 name = "wasm-utxo"