Keep the URL suffix when linking to the booking form

The event alias is passed as route parameter instead of being appended
to the page URL, so a site with a suffix such as .html gets
/kurs/anmeldung/<alias>.html instead of /kurs/anmeldung.html/<alias>.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/Booking/BookingUrlBuilder.php

@@ -22,13 +22,8 @@ class BookingUrlBuilder
 
     public function bookingUrl(BookingEvent $event, CalendarConfig $calendar): string
     {
-        $url = $this->pageUrl($calendar->bookingPage);
-
-        if ('' === $url) {
-            return '';
-        }
-
-        return rtrim($url, '/').'/'.($event->alias ?: $event->id);
+        // Als Routen-Parameter, damit ein URL-Suffix (z. B. .html) hinter dem Alias steht
+        return $this->pageUrl($calendar->bookingPage, ['parameters' => '/'.($event->alias ?: $event->id)]);
     }
 
     public function inquiryUrl(BookingEvent $event, CalendarConfig $calendar): string
@@ -42,7 +37,10 @@ class BookingUrlBuilder
         return $url.(str_contains($url, '?') ? '&' : '?').'event='.$event->id;
     }
 
-    public function pageUrl(int $pageId): string
+    /**
+     * @param array<string, mixed> $parameters
+     */
+    public function pageUrl(int $pageId, array $parameters = []): string
     {
         if ($pageId < 1) {
             return '';
@@ -56,7 +54,7 @@ class BookingUrlBuilder
         }
 
         try {
-            return $this->urlGenerator->generate($page);
+            return $this->urlGenerator->generate($page, $parameters);
         } catch (\Throwable) {
             return '';
         }