Add types for normalizeP5ReferenceLinks helper

Author: rakesh2OO5

src/layouts/ReferenceItemLayout.astro

@@ -92,7 +92,7 @@ const { showBanner, englishUrl } = checkTranslationBanner(
 );
 // Normalizes malformed p5.* reference anchors (e.g. "#/p5.Element")
 // to proper reference routes ("/reference/p5/p5.Element/")
-function normalizeP5ReferenceLinks(html) {
+function normalizeP5ReferenceLinks(html: string | undefined): string | undefined {
   if (!html) return html;
   return html.replace(
     /href="#\/(p5\.[^"]+)"/g,