feat: implement hx-boost for reliable loading indication

src/Form/Service/ParticipantInsuranceFieldHandler.php

@@ -193,6 +193,11 @@ class ParticipantInsuranceFieldHandler extends AbstractParticipantFieldHandler
 
         // Handle form resubmission with existing insurance (automatic reassignment check)
         if (null !== $currentInsurance && null !== $selectedInsuranceId) {
+            // Preserve "no insurance" selection during resubmission
+            if ($currentInsurance->isNoInsurance()) {
+                return;
+            }
+
             // Check if current insurance is still eligible with updated participant data
             $eligibleInsurances = $this->insuranceService->getEligibleInsurances($selectableInsurances, $participant, $bookingDto, $travelPrice);
             $isCurrentInsuranceStillEligible = $this->isInsuranceInList($currentInsurance, $eligibleInsurances);