Refund flow: allow immediate refund after settlement and add refund reason

Users want to be able to refund a payment without a multi-step "push to get notified when settled then refund" flow—instead, once a payment settles, they want to be able to refund it immediately. They also want a controlled list of refund reasons (e.g. service not performed, CSI) that is consistent across brands and can be reported on; later, reasons can be mapped to different handling in QuickBooks.

Why it matters: Simplifies refund handling for client care and ensures consistent reporting and future accounting treatment by reason.