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/build/templates/app-page.d.ts

@@ -0,0 +1,13 @@
+import type { IncomingMessage, ServerResponse } from 'node:http';
+import { AppPageRouteModule } from '../../server/route-modules/app-page/module.compiled';
+import GlobalError from 'VAR_MODULE_GLOBAL_ERROR';
+export { GlobalError };
+export declare const __next_app__: {
+    require: (id: string | number) => unknown;
+    loadChunk: (id: string | number) => Promise<unknown>;
+};
+export * from '../../server/app-render/entry-base';
+export declare const routeModule: AppPageRouteModule;
+export declare function handler(req: IncomingMessage, res: ServerResponse, ctx: {
+    waitUntil: (prom: Promise<void>) => void;
+}): Promise<void | null>;