Include USD equivalent amount on the refund object/payload

Summary

For non-USD payments, the refund object/webhook payload only carries the refunded amount in the presentment currency (e.g. BDT). It does not include the USD equivalent of the refunded amount.

The dashboard already shows the refunded USD figure (e.g. "37 of 39 USD refunded"), but that value isn't exposed anywhere in the refund payload — only usd_equivalent_amount exists on the payment object.

Problem

Merchants storing refunds in their own DB currently have to derive the refunded USD value themselves by applying the refund-to-payment ratio against the payment's usd_equivalent_amount. This is error-prone and easy to get wrong for partial refunds.

Request

Expose a usd_equivalent_amount (or equivalent settlement/USD figure) directly on the refund object and refund webhook payloads, so the refunded amount in USD is available out of the box without any client-side calculation.

Impact

• Removes a manual, error-prone calculation for every merchant reconciling non-USD refunds.
• Makes refund reporting consistent with the payment object, which already exposes usd_equivalent_amount.

Raised on behalf of a merchant reconciling non-USD (BDT/EUR) refunds into their own Payments table.