Wallet / Credit 3rd party calls on cart and checkout

Added the ability for third-party apps to override the core wallet and credit functionality on cart and checkout.

How it benefits the Merchant

This gives merchants flexibility to integrate custom or third-party wallet and credit systems into their cart and checkout experience.

Potential FAQs

Q: Do I need a third-party app to use this?

A: Yes — this feature enables third-party apps to override wallet/credit functionality, so it requires an integrated app to take effect.

Q: Will this change the default wallet and credit behavior if I don't use a third-party app?

A: No — without a third-party override, the core wallet and credit functionality should continue to work as before.