feat(passenger): simplify ParticularityTransport mobility to three values

Replace the legacy mobility enum with SANS_FAUTEUIL, FAUTEUIL_PLIABLE, and FAUTEUIL_NON_PLIABLE in vsn-common. Update passenger import mapping and wheelchair counting to use the new values, and expose display labels via getDisplayName(). Remove the duplicate enum shadow in user-service. Legacy French labels are mapped on import until database migration is applied.