[SDK] buildUnwrapCalldata + UnwrapERC7984 explain/verify

[0xPrabh]

Description

Adds buildUnwrapCalldata(from, to, encryptedAmount, inputProof) and UnwrapERC7984 transaction support for the ERC-7984 unshield path.

• Encodes unwrap(address,address,bytes32,bytes) with selector 0x5bf4ef06
• Validates checksummed from/to, 32-byte encryptedAmount, non-empty inputProof
• Adds TransactionType.UnwrapERC7984 with builder + classifyTransaction mapping
• Erc7984Token.verifyTransaction unwrap branch (direct + sendMultiSig); self-directed from == to == baseAddress
• Does not set gasLimit (WP owns gas)

Issue Number

CHALO-1155

Parent: CHALO-1135

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

• yarn workspace @bitgo/abstract-eth unit-test --grep "buildUnwrapCalldata|Method IDs" (13 passing)
• BITGOJS_TEST_PASSWORD=password yarn workspace @bitgo/sdk-coin-eth unit-test --grep "UnwrapERC7984|verifyTransaction – Unwrap" (12 passing)
• eslint on touched files

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My commits follow Conventional Commits and I have properly described any BREAKING CHANGES
• The ticket or github issue was included in the commit message as a reference
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Made with Cursor

[linear-code]

CHALO-1155