Payment method updates for duplicate saved cards

In some cases, how a Payment methods record was created left the customer without permission to update it. Duplicate detection could return the existing method id after a conflict, then the follow-up update failed with “payment method not exist.” Those permission paths are fixed for merchant-created methods the customer needs to update.

• When a POST conflicts because the card already exists, PATCH on the returned id succeeds for methods created on the customer's behalf that previously lacked update access.
• This was situational: methods already created with the right ownership were unaffected.