feat: implement skeleton loading across all dynamic sections

Added a shimmering Skeleton component. Integrated loading states for Hero, About (Bento Grid), Reading Log, Projects Archive, and Library pages for a premium UX.

app/_ui/ProjectDetailClient.tsx

@@ -8,6 +8,7 @@ import ReactMarkdown from "react-markdown";
 import { useTranslations } from "next-intl";
 import Image from "next/image";
 import { useRouter } from "next/navigation";
+import { Skeleton } from "../components/ui/Skeleton";
 
 export type ProjectDetailData = {
   id: number;