Remove a payment card from the scope

Removes the selected payment card from the scope ("Remove card" in the Payment methods page). Deletion revokes the processor token and removes the card from the scoped list; the card disappears from the auto-pay configuration. Removal is blocked while the card is load-bearing — e.g. it is the default card backing auto-pay for open UNPAID/OVERDUE invoices references it — and the blocker is reported to the caller instead of leaving billing in an unpayable state. Validation: paymentMethodId must reference an existing payment method visible in the scope (otherwise 404 NOT_FOUND); deletion must not be blocked by an unresolved dependency — default card with auto-pay enabled and open invoices, or a pending charge in flight (otherwise 409 DEPENDENCY_BLOCKED with the concrete blocker); the caller must hold destructive billing permissions (otherwise 403 FORBIDDEN). Async & state: Asynchronous soft delete; returns 202 with an Operation that moves pending → running → succeeded (token revoked, card removed from the list; a resource.updated SSE frame with kind: payment_method, patch: {status: deleting} then a terminal removal frame are emitted) or failed (the card stays queryable and recoverable in its prior state). Errors: 401 unauthenticated; 403 caller lacks destructive billing permission; 404 unknown paymentMethodId in the scope; 409 DEPENDENCY_BLOCKED when the card backs auto-pay for open invoices or has a charge in flight; 500 on revocation failure. Idempotency/Concurrency: This operation does not use Idempotency-Key; it may be omitted and a sent one is ignored. The card is hard-deleted inline and a new already-SUCCEEDED Operation is returned; repeating the delete after it succeeded answers 404 NOT_FOUND because the card is gone. This operation does not check If-Match; a sent one is ignored.