Gap planning

Use POST /api/utm-gap-plan to assess whether a gap is practically usable after accounting for travel and protected transition time.

{
  "from": "MN",
  "to": "IB",
  "term": "Fall",
  "weekday": "Wednesday",
  "startTime": 660,
  "endTime": 780
}

Gap planning is deterministic. Treat its uncertainty and route-coverage fields as part of the contract.