feat: persist travel snapshots and refresh extended availability

src/BusProNet/XmlParser/TravelParser.php

@@ -67,6 +67,9 @@ class TravelParser extends AbstractParser
         $travel->dateFrom = $dateFrom;
         $travel->dateTo = $dateTo;
         $travel->code = $this->getAttrOrNullValue($node, 'code');
+        $travel->productId = null !== $this->getAttrOrNullValue($node, 'idprodukt')
+            ? (int) $this->getAttrOrNullValue($node, 'idprodukt')
+            : null;
 
         // Parse product code from parent reise node using DOM
         $domNode = $node->getNode(0);