feat: added @x402/evm-contracts for evm permit2 update

[CarsonRoscoe]

THE CONTRACTS IN THIS PR HAVE YET TO BE AUDITED. ONLY DEPLOY TO TEST NETWORKS AT THIS TIME

Description

In order to implement #769, an x402Permit2Proxy contract must be written and deployed.

This PR adds a package evm-contracts, which both acts as a hardhat project for smart contract development, while also acting as the npm module which exports the ABI & addresses of the deployed contracts

Base Sepolia Deployment

Tests

Added united tests & base-sepolia forked integration tests

Checklist

• I have formatted and linted my code
• All new and existing tests pass
• My commits are signed (required for merge) -- you may need to rebase if you initially pushed unsigned commits

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1

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Project	Deployment	Review	Updated (UTC)
x402	Ready	Preview, Comment	Jan 7, 2026 2:42am