fix: notFound() on missing post, await params for Next.js 15

app/posts/[slug]/page.tsx

@@ -8,9 +8,7 @@ import rehypePrettyCode from "rehype-pretty-code";
 import rehypeSlug from "rehype-slug";
 
 interface PageProps {
-  params: {
-    slug: string;
-  };
+  params: Promise<{ slug: string }>;
 }
 
 export async function generateStaticParams() {
@@ -19,14 +17,16 @@ export async function generateStaticParams() {
 }
 
 export async function generateMetadata({ params }: PageProps) {
-  const postData = await getPostData(params.slug);
+  const { slug } = await params;
+  const postData = await getPostData(slug);
   return {
     title: `${postData.title} | Gabriel's Kaszewski Blog`,
   };
 }
 
 export default async function Post({ params }: PageProps) {
-  const postData: PostData = await getPostData(params.slug);
+  const { slug } = await params;
+  const postData: PostData = await getPostData(slug);
 
   return (
     <div className="mx-auto max-w-5xl">