feat: prefer discounted transportation services

addresses #869axbjbz

src/BusProNet/Model/Travel.php

@@ -48,7 +48,7 @@ class Travel
 
     /**
      * Travel booking status from BusProNet API.
-     * Possible values: 'Frei', 'Anfrage', 'Buchungsstop'
+     * Possible values: 'Frei', 'Anfrage', 'Buchungsstop'.
      */
     #[Groups(['api:single'])]
     public ?string $status = null;
@@ -153,8 +153,12 @@ class Travel
      * Filters transportation services based on travel direction and optionally
      * by availability. Services are sorted by subtype.
      *
+     * Note: PKW/CAR filtering based on booking context is NOT applied here.
+     * That filtering happens dynamically in ParticipantFieldOptionsProvider using
+     * per-booking availability calculations from ServiceAvailabilityCalculator.
+     *
      * @param string $direction       The travel direction to filter by
-     * @param bool   $filterAvailable Whether to include only available services
+     * @param bool   $filterAvailable Whether to include only available services (API availability)
      *
      * @return array<int, Service> The filtered and sorted transportation services
      */