VIP event email status and sends

These operations support private invitation events and invitation-capacity VIP meals,
including breakfasts, lunches, and dinners. The caller must manage the event.

• GET /api/agents/v1/vip_event_emails/list: requires meetup_token.
  Optionally filter by client_token; paginate using limit (maximum 100)
  and offset. Returns all ten attendee lifecycle types even when unavailable:
  invitation, confirmation, waitlist, cancellation, five_day_reminder, day_before,
  day_of, check_in, survey, and survey_results.
• GET /api/agents/v1/vip_event_emails/preview: requires meetup_token,
  client_token, and message_type. Returns the exact stored sent copy or
  current template with send eligibility.
• POST /api/agents/v1/vip_event_emails/send: requires the same three fields
  and confirm: true. Sends only that attendee’s selected unsent email.
  A repeated send returns email_not_sendable (HTTP 409); it never resends a
  delivered type. In-progress and unknown outcomes also block retries.

The catalog includes sent, sent_at, mail_log_token, delivery_state,
delivery_label, applicable, sendable, blocked_reason, and event timezone.
sent means provider acceptance, while delivery_label separately reports
provider delivery, bounce, or complaint evidence. Invitation sends made externally
remain in the invitation ledger and do not falsely count as a platform email.

Day-before emails may be triggered throughout the previous event-local date,
including 7 PM for an 8 AM breakfast. Automatic delivery normally begins at the
same local time the previous day and expires at event-local midnight.
Day-of emails require the event’s local date and close one hour before start.
An 8 AM event has an automatic window from 6 AM until 7 AM, exclusive.
A final timing check runs immediately before the provider call to prevent stale
queued reminders crossing midnight or the advance-notice cutoff.

Invitation, confirmation, and waitlist messages require a future event.
Check-in follow-up requires check-in and the existing follow-up window.
Survey emails require the event to have ended and an open, unanswered survey;
results require available community results and the recipient’s email preference.

A named organizer invitation to the same address establishes email eligibility
for that VIP event. It does not change account verification. Bounce, complaint,
workspace email-disable, and applicable subscription rules still apply.