feat: list and respect all surcharges

src/BusProNet/ApiResponseParser/BookingResponseParser.php

@@ -226,11 +226,7 @@ class BookingResponseParser
         foreach ($xml->zuschlag as $item) {
             $attributes = $item->attributes();
 
-            $label = (string) $attributes['bezeichnung'];
-            // Skip invalid entries
-            if (empty($label)) {
-                continue;
-            }
+            $label = empty($attributes['bezeichnung']) ? 'unbekannt' : (string) $attributes['bezeichnung'];
 
             $surcharge = new Surcharge();
             $surcharge->label = $label;

src/BusProNet/Model/Booking.php

@@ -121,6 +121,13 @@ class Booking
         return $price;
     }
 
+    public function getSurchargesForParticipant(int $participantIndex): array
+    {
+        return array_filter($this->surcharges, function (Surcharge $surcharge) use ($participantIndex) {
+            return in_array($participantIndex, $surcharge->mapping);
+        });
+    }
+
     public function isEditable(): bool
     {
         return $this->travelDate > new \DateTimeImmutable() && false === in_array($this->status, ['S', 'U']);