Answer a pending tool approval

Answers a consent requirement returned by a mirrored tool route. A caller declares its answer channel with X-ToolPiper-Approval-Channel: rest on the original request. The refusal carries an approval id; after approval, repeat the original request with X-ToolPiper-Approval-Id: <id>. The authenticated client key must match the client that requested approval. An allow-once answer admits only the same tool and canonical JSON arguments once. JSON object key order does not change the argument binding. An allow-session answer, where the refusal's offeredAnswers lists it, admits the one call and leaves a rule allowing that tool for the same client's session, until ToolPiper exits or that client loses authority; grant is session when the rule was written and once otherwise. It saves nothing lasting. Every invocation still meets the current authorization gates. An always-allow or always-deny answer is accepted only where the refusal's offeredAnswers lists it. Always deny refuses the call and saves the rule at once. Always allow admits the one call as allow-once does and asks ToolPiper to save the rule, which the person confirms on the Mac; the reply waits for that and its remembered says saved, or, when it was not confirmed, session_only where a session answer is listed and nothing where it is not. Pending approvals and unconsumed once approvals expire after 45 seconds; an answer at exactly 45 seconds is refused. Only the first answer is accepted. Device-owner authentication cannot be answered through this endpoint. Callers that do not declare the REST channel use native approval on the Mac. An operation that judges further work (arming a schedule judges the tool each fire runs) can need a card for each: the repeated request answers consent_required again with continues naming the approval it carried. Answer that one and repeat the request with its id; each earlier call is admitted once by it, and an earlier answer never admits a later call's arguments.