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/send-payload.d.ts

@@ -0,0 +1,12 @@
+import type { IncomingMessage, ServerResponse } from 'http';
+import type RenderResult from './render-result';
+import type { CacheControl } from './lib/cache-control';
+export declare function sendEtagResponse(req: IncomingMessage, res: ServerResponse, etag: string | undefined): boolean;
+export declare function sendRenderResult({ req, res, result, generateEtags, poweredByHeader, cacheControl, }: {
+    req: IncomingMessage;
+    res: ServerResponse;
+    result: RenderResult;
+    generateEtags: boolean;
+    poweredByHeader: boolean;
+    cacheControl: CacheControl | undefined;
+}): Promise<void>;