Request Call

Record that this visitor wants to book a paid call with this profile.

Returns {"status": "requested", "price_cents": n, "requested_at": ...}. Idempotent per (visitor, profile, UTC day): a second press returns the first row rather than writing another, so a double-tap is not two requests in the operator's queue.

404 for an unknown or unpublished handle and for a profile that does not offer calls -- one answer, so "does this person sell calls" cannot be probed on a profile the caller cannot otherwise see. 400 for one's own profile.