docs: add inline documentation where missing

src/BusProNet/DataProcessor/PickupPlanningTransformer.php

@@ -4,6 +4,13 @@ declare(strict_types=1);
 
 namespace App\BusProNet\DataProcessor;
 
+/**
+ * Transforms raw pickup planning data into structured travel-indexed pickup information.
+ *
+ * Processes JSON payload from the CMS pickup planning endpoint, filtering for outbound
+ * trips (HIN direction) and grouping pickups by travel code. Each pickup includes city,
+ * location, and datetime, sorted chronologically per travel code.
+ */
 class PickupPlanningTransformer
 {
     /**