v2: fix paywall exports and wallet selection

[phdargen]

Description

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

[vercel[bot]]

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

A member of the Team first needs to authorize it.

[apmcdermott]

Your changes have been incorporated into https://github.com/coinbase/x402/pull/705 🙌