feat: add title-only search mode

Adds a titleOnly flag to page search: the Postgres driver matches
titles via trigram-indexed unaccented LIKE ranked by word_similarity,
and a Match filter in the search spotlight switches between everything
and title-only matching.

apps/client/src/features/search/components/search-spotlight.tsx

@@ -33,6 +33,7 @@ export function SearchSpotlight({ spaceId }: SearchSpotlightProps) {
     contentType?: string;
     creatorId?: string | null;
     labelIds?: string[];
+    titleOnly?: boolean;
   }>({
     contentType: "page",
   });
@@ -58,6 +59,10 @@ export function SearchSpotlight({ spaceId }: SearchSpotlightProps) {
       params.labelIds = filters.labelIds;
     }
 
+    if (filters.titleOnly) {
+      params.titleOnly = true;
+    }
+
     return params;
   }, [debouncedSearchQuery, filters]);