fix(booking-import): every leg of a connecting flight keeps its own seat

The grouped flight wrote a seat only on the booking itself, from the first
segment. Each leg in metadata.legs now carries the seat of its own segment,
which the planner and the PDF already show per leg.

server/src/nest/booking-import/kitinerary-mapper.ts

@@ -304,11 +304,13 @@ function mapFlightGroup(legs: KiReservation[], source: ParsedBookingItem['source
     const arrEp = makeEndpoint(f.arrivalAirport, isLast ? 'to' : 'stop', onward.time, onward.date);
     if (arrEp) endpoints.push(arrEp);
     const airline = f.airline?.name ?? f.airline?.iataCode ?? '';
+    const { seat } = segmentDetail(legs[i]);
     metaLegs.push({
       from: iataOf(f.departureAirport),
       to: iataOf(f.arrivalAirport),
       ...(airline ? { airline } : {}),
       ...(f.flightNumber ? { flight_number: f.flightNumber } : {}),
+      ...(seat != null ? { seat } : {}),
       dep_time: splitIso(f.departureTime).time,
       arr_time: arr.time,
     });