chore: enforce common prop typing style

app/[[...slug]]/page.tsx

@@ -19,9 +19,9 @@ export async function generateStaticParams() {
   }
 }
 
-type Props = {
+export interface Props {
   params: Promise<{ slug?: string[] }>;
-};
+}
 
 /**
  * Portfolio page — one route per section, sections list always visible.