feat: finalize voucher handling and discount display in summary and overview

src/Controller/Booking/Create/Step3Controller.php

@@ -6,6 +6,7 @@ namespace App\Controller\Booking\Create;
 
 use App\BusProNet\ApiClient;
 use App\BusProNet\Exception\TimeoutException;
+use App\BusProNet\Model\BookingResponse;
 use App\BusProNet\Model\Notification;
 use App\Controller\Booking\Traits\BookingCreateTrait;
 use App\Controller\Booking\Traits\BookingExceptionHandlerTrait;
@@ -121,16 +122,22 @@ class Step3Controller extends AbstractController
                 }
 
                 // Validate price match (rounded to cent precision to avoid floating-point errors)
+                // API gesamtpreis includes promotional/goodwill voucher discounts (negative price items),
+                // but NOT purchase vouchers (those reduce restzahlung, not gesamtpreis)
                 $apiTotal = round($inquiryResponse->totalPrice ?? 0.0, 2);
-                $calculatedTotal = round($this->priceCalculator->calculateGrandTotal($bookingCreateDto), 2);
+                $calculatedSubtotal = round($this->priceCalculator->calculateGrandTotal($bookingCreateDto), 2);
+                $promoGoodwillDiscount = round($inquiryResponse->getVoucherDiscountFromPrices(), 2);
+                $expectedTotal = round($calculatedSubtotal - $promoGoodwillDiscount, 2);
 
-                if ($apiTotal !== $calculatedTotal) {
+                if ($apiTotal !== $expectedTotal) {
                     return $this->handleApiError(
                         'Price mismatch detected - payload incomplete',
                         [
                             'apiTotal' => $apiTotal,
-                            'calculatedTotal' => $calculatedTotal,
-                            'difference' => abs($apiTotal - $calculatedTotal),
+                            'calculatedSubtotal' => $calculatedSubtotal,
+                            'promoGoodwillDiscount' => $promoGoodwillDiscount,
+                            'expectedTotal' => $expectedTotal,
+                            'difference' => abs($apiTotal - $expectedTotal),
                         ],
                         'Ein technischer Fehler ist aufgetreten.',
                         $bookingCreateDto,
@@ -225,11 +232,11 @@ class Step3Controller extends AbstractController
      * an inquiry rather than showing an error. This handles scenarios where
      * availability changes between booking initialization and validation.
      *
-     * @param \App\BusProNet\Model\BookingResponse $response The API response
+     * @param BookingResponse $response The API response
      *
      * @return bool True if should fallback to inquiry mode, false if should show error
      */
-    private function shouldFallbackToInquiryMode(\App\BusProNet\Model\BookingResponse $response): bool
+    private function shouldFallbackToInquiryMode(BookingResponse $response): bool
     {
         // Check for "nicht möglich" status + inquiry suggestion in message
         if ('nicht möglich' !== $response->status) {