feat(wasm-utxo): add BCH fork ID support for BCH, XEC, BSV, BTG

Implement fork ID support for Bitcoin Cash-style networks to enable proper
signing and verification. This includes:

- Use fork ID-aware signing for BCH (0), BTG (79), XEC (0), and BSV (0)
- Update miniscript dependency to use forkid-compatible version
- Modify PSBT functions to use the appropriate sighash algorithm
- Ensure replay protection inputs use correct sighash calculation
- Add tests to verify sign→verify roundtrip works correctly

Issue: BTC-2656

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

Author: OttoAllmendinger

packages/wasm-utxo/Cargo.lock

@@ -16,7 +16,7 @@ all = "warn"
 [dependencies]
 wasm-bindgen = "0.2"
 js-sys = "0.3"
-miniscript = { git = "https://github.com/BitGo/rust-miniscript", tag = "miniscript-13.0.0-opdrop" }
+miniscript = { git = "https://github.com/BitGo/rust-miniscript", tag = "miniscript-13.0.0-opdrop-forkid" }
 bech32 = "0.11"
 musig2 = { version = "0.3.1", default-features = false, features = ["k256"] }
 getrandom = { version = "0.2", features = ["js"] }