fix(canonical): slugless canonical for singletons; drop volatile listing query params

Singletons are served at their slugless listing URL (ListingController
forwards a singleton listing to the record), but getCanonicalRouteAndParams
returned the record-detail route, exposing two URLs for identical content
(/o-spolecnosti and /o-spolecnosti/o-nas). Canonicalize singletons to the
slugless /{singularSlug} URL instead.

Also stop merging listing query params (order/status/filters) into the
listing canonical, where they appeared as ?order=-createdAt&status=published.

Author: Vondry

src/Controller/Frontend/ListingController.php

@@ -69,13 +69,15 @@ public function listing(Request $request, ContentRepository $contentRepository,
 
         $records = $this->setRecords($content, $amountPerPage, $page);
 
-        // Set canonical URL
+        // Set canonical URL. Note: query params (order/status/filters from
+        // parseQueryParams) are intentionally NOT merged in — they are volatile and
+        // would pollute the canonical (e.g. ?order=-createdAt&status=published).
         $this->canonical->setPath(
             'listing_locale',
-            array_merge([
+            [
                 'contentTypeSlug' => $contentType->get('slug'),
                 '_locale' => $request->getLocale(),
-            ], $params)
+            ]
         );
 
         // Render

src/Utils/ContentHelper.php

@@ -68,6 +68,21 @@ private function getCanonicalRouteAndParams(Content $record, ?string $locale = n
             ];
         }
 
+        // Singletons are served at their slugless listing URL: ListingController
+        // forwards a singleton "listing" to the record. Canonicalize to that URL
+        // (`/{singularSlug}`) instead of the record-detail route
+        // (`/{singularSlug}/{slug}`), so a singleton has a single, slugless URL
+        // rather than two URLs serving identical content.
+        if ($record->getDefinition()->get('singleton')) {
+            return [
+                'route' => 'listing_locale',
+                'params' => [
+                    'contentTypeSlug' => $record->getContentTypeSingularSlug(),
+                    '_locale' => $locale,
+                ],
+            ];
+        }
+
         return [
             'route' => $record->getDefinition()->get('record_route'),
             'params' => [