VSN-2863/feat(passenger): add retrieveScheduleSummariesByUuids projection endpoint
Expose POST /passenger/retrieveScheduleSummariesByUuids returning a slim PassengerScheduleSummaryDTO (uuid, firstName, lastName, establishmentId/name) for the "Emploi du temps" screen, instead of hydrating the heavy PassengerDTO.
- Repository: findScheduleSummariesByUuids uses a scalar JPQL constructor projection (LEFT JOIN establishmentTransportSchedules) so the eager Passenger graph is never loaded; the service keeps the first row per uuid, preserving the existing "first establishment schedule" behaviour.
- Service: getPassengerScheduleSummariesByUuids resolves each distinct establishment id once via adminService, and tolerates an isolated lookup failure (logged) rather than failing the whole list. Empty/null input throws PASSENGER_ID_LIST_EMPTY.
- Controller + Paths: new GET_PASSENGER_SCHEDULE_SUMMARIES_BY_UUIDS endpoint.
- New DTO: PassengerScheduleSummaryDTO.