feat: token implementation

[alexbarnsley]

Summary

https://app.clickup.com/t/86e00vrhr
https://app.clickup.com/t/86e00vrmd
https://app.clickup.com/t/86e00vrn9

Checklist

• Documentation (if necessary)
• Tests (if necessary)
• Ready to be merged

[Copilot]

Pull request overview

Adds token-transfer ABI support and convenience encoding/building helpers to generate ERC-20 transfer calldata and submit it as an EvmCall transaction.

Changes:

• Add TOKEN contract ABI type + Abi.Token.json artifact and register it in AbiBase.
• Introduce TransactionEncoder utility for encoding common contract call payloads, including token transfer.
• Add TokenTransferBuilder + corresponding unit tests for payload construction and signing/verifying.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tests/Unit/Utils/TransactionEncoderTest.php	Adds unit tests for encoded payload outputs (incl. token transfer) and invalid-address rejection.
tests/Unit/Transactions/Builder/TokenTransferBuilderTest.php	Adds tests validating token transfer builder calldata and signature verification.
src/Utils/TransactionEncoder.php	New utility for ABI-encoding calldata for multipayment, token transfer, usernames, and consensus calls.
src/Utils/AbiBase.php	Registers ContractAbiType::TOKEN -> Abi.Token.json path.
src/Utils/Abi/json/Abi.Token.json	Adds token ABI artifact containing transfer (and related) function definitions.
src/Transactions/Builder/TokenTransferBuilder.php	Adds builder to construct EvmCall token transfer transactions using ABI encoding.
src/Enums/ContractAbiType.php	Adds TOKEN enum case.
src/Enums/AbiFunction.php	Adds TRANSFER function enum and maps it to EvmCall.

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