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/server/lib/patch-set-header.d.ts

@@ -0,0 +1,13 @@
+import { type NextIncomingMessage } from '../request-meta';
+type PatchableResponse = {
+    setHeader(key: string, value: string | string[]): PatchableResponse;
+};
+/**
+ * Ensure cookies set in middleware are merged and not overridden by API
+ * routes/getServerSideProps.
+ *
+ * @param req Incoming request
+ * @param res Outgoing response
+ */
+export declare function patchSetHeaderWithCookieSupport(req: NextIncomingMessage, res: PatchableResponse): void;
+export {};