feat: simplify handling of ski pass service

src/BusProNet/Model/Booking.php

@@ -150,6 +150,29 @@ class Booking
         return null;
     }
 
+    /**
+     * Retrieves ski pass for a specific participant.
+     *
+     * Since each participant can only have one ski pass, this method returns
+     * the single ski pass assigned to the participant or null if none is assigned.
+     *
+     * @param int $participantIndex The participant index to search for
+     *
+     * @return Service|null The participant's ski pass or null if not found
+     */
+    public function getSkiPassForParticipant(int $participantIndex): ?Service
+    {
+        $skiPasses = $this->getAdditionalServicesByGroup('SPA');
+
+        foreach ($skiPasses as $service) {
+            if (in_array($participantIndex, $service->mapping)) {
+                return $service;
+            }
+        }
+
+        return null;
+    }
+
     /**
      * Retrieves room assignment for a specific participant.
      *