Refactor settle function to simplify signature handling

[giuseppecrj]

Description

Removed unnecessary parsing of ERC-6492 signatures in the settle function. The function now directly uses the payload signature, streamlining the code and improving readability. This change allows for modular accounts (ERC6900) who use different signature methods to work properly without breaking compatibility.

Tests

pnpm run test

Checklist

• [X] I have formatted and linted my code
• [X] All new and existing tests pass
• [X] 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

[vercel[bot]]

@giuseppecrj is attempting to deploy a commit to the Coinbase Team on Vercel.

A member of the Team first needs to authorize it.

[phdargen]

Thanks a lot for the suggestion @giuseppecrj! The signature handling was improved in https://github.com/coinbase/x402/pull/713 and should cover this