Allow Payment Method Deletion When Currently Blocked (manual-renewal & only-method-on-file)

🔍 Problem Statement

Customers and admins cannot delete a saved payment method in situations where keeping it provides no functional benefit and blocks legitimate requests: (a) when the method is tied only to manual-renewal subscriptions — which do not process recurring payments, so requiring a replacement is pointless — and (b) when it is the only payment method on file (including ACH), which blocks admins from honouring customer data-removal requests.

💡 User Story

As a customer or Pelcro admin, I want to remove a saved payment method in these currently-blocked scenarios without being forced to add a replacement, so that I can clean up unused methods and fulfil data-removal requests.

🎯 Definition of Done (DoD)

• ✔ Allow deletion of a payment method tied only to manual-renewal subscription(s) without requiring a replacement.
• ✔ Allow admin removal of the only saved payment method on an account (including ACH); any linked subscriptions transition to manual/invoice billing.
• ✔ This change will impact UI / API — the payment-method management UI and the payment-method resource (Core API).