chore: major code cleanup and type safety using phpstan

src/Controller/Booking/Create/Step1Controller.php

@@ -53,7 +53,8 @@ class Step1Controller extends AbstractController
         $oldRoomSelectionSnapshot = $this->bookingSessionService->getOrCreateBaselineSnapshot($request, $bookingCreateDto);
 
         // Validate step access - allow step 1 or redirect to current step
-        if ($redirect = $this->validateStepAccess($bookingCreateDto, 1)) {
+        $redirect = $this->validateStepAccess($bookingCreateDto, 1);
+        if (null !== $redirect) {
             return $redirect;
         }