Delete a vault item and invalidate its secret value

Unresolved payment operations normally block deletion, including operations on child cards of a wallet. Deleting a connected Kernel wallet first blocks new payments on it, then removes its enrolled card. If that fails, the wallet is kept and keeps refusing payments; retry the deletion. A Link, Kernel or Shop Pay card in recovery_required for issuance, or an AgentCard card in recovery_required whose checkout create response returned no authorization ID, may be explicitly abandoned by deleting that card directly; deleting its wallet or vault remains blocked until the card is deleted. Deleting or recreating an item is not proof that a payment did not occur. Deleting a managed auth credential item leaves the connection and its saved credential unchanged.