Per-recipient tracking of a survey email campaign: query campaign (the EMAIL outbound id), cursor,
limit (≤ 100). Returns { items: [{ contact, sentAt, opened, openedAt, answered, answeredFromEmail, responseId, responseStatus }], nextCursor? }, newest send first. Email surveys are a paid channel:
402 on Free (who answered would name respondents beyond the survey's first 10 responses).
Bearer <token>.Ok