feat(blog): add file-based blog with dynamic slugs, MDX content and layout shell

- Introduced blog routing using Next.js App Router
- Implemented dynamic [slug] pages for blog posts
- Added MDX-based content loading via lib/posts
- Integrated shared TopBar layout with navigation
- Established clear content, lib and component separation

apps/public-web/node_modules/next/dist/client/use-intersection.d.ts

@@ -0,0 +1,8 @@
+type UseIntersectionObserverInit = Pick<IntersectionObserverInit, 'rootMargin' | 'root'>;
+type UseIntersection = {
+    disabled?: boolean;
+} & UseIntersectionObserverInit & {
+    rootRef?: React.RefObject<HTMLElement | null> | null;
+};
+export declare function useIntersection<T extends Element>({ rootRef, rootMargin, disabled, }: UseIntersection): [(element: T | null) => void, boolean, () => void];
+export {};