Add new payment method to all recurring invoices

Payment methods arrive detached from recurring invoices, causing failed charges. It attaches the gateway to active recurring invoices and creates billing checklists before the next run.

Overview

Unattached payment methods create charge failures and extra tickets for billing and support. This flow assigns the new gateway to active recurring invoices and spins up billing checklists, so billing staff and support coordinators can collect balances before the next billing run.