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/experimental/testmode/fetch.d.ts

@@ -0,0 +1,6 @@
+import { type TestRequestReader } from './context';
+type Fetch = typeof fetch;
+export declare const reader: TestRequestReader<Request>;
+export declare function handleFetch(originalFetch: Fetch, request: Request): Promise<Response>;
+export declare function interceptFetch(originalFetch: Fetch): () => void;
+export {};