fix: ensure drop-offs are submitted when same as pickups

src/Form/Service/ParticipantDropOffFieldHandler.php

@@ -13,7 +13,7 @@ use App\Form\Service\Abstract\AbstractParticipantFieldHandler;
  *
  * Drop-off behavior depends on the transportation combination:
  * - BUS+BUS: drop-off is gated behind a "differentDropOff" checkbox.
- *   When unchecked, BusProNet defaults to the same location as the pickup.
+ *   When unchecked, the system assigns the same location as the pickup.
  * - PKW+BUS: drop-off is shown directly (no pickup field, no checkbox needed).
  * - BUS+PKW / PKW+PKW: no drop-off applicable, fields are cleared.
  */
@@ -54,14 +54,15 @@ class ParticipantDropOffFieldHandler extends AbstractParticipantFieldHandler
             return;
         }
 
-        if ($hasOutboundBus) {
+        if (true === $hasOutboundBus) {
             // BUS+BUS: gated by differentDropOff checkbox
-            $checkboxValue = $this->getFieldValue($submittedData, 'differentDropOff');
-            $isChecked = true === $checkboxValue || '1' === $checkboxValue || 1 === $checkboxValue;
+            $isChecked = $this->normalizeCheckboxValue($this->getFieldValue($submittedData, 'differentDropOff'));
 
             if (false === $isChecked) {
-                $participant->dropOff = null;
                 $participant->differentDropOff = false;
+                $participant->dropOff = null !== $participant->pickup
+                    ? ($bookingDto->travel->dropOffs[$participant->pickup->id] ?? null)
+                    : null;
 
                 return;
             }