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/static-paths/pages.d.ts

@@ -0,0 +1,9 @@
+import type { GetStaticPaths } from '../../types';
+import type { StaticPathsResult } from './types';
+export declare function buildPagesStaticPaths({ page, getStaticPaths, configFileName, locales, defaultLocale, }: {
+    page: string;
+    getStaticPaths: GetStaticPaths;
+    configFileName: string;
+    locales?: readonly string[];
+    defaultLocale?: string;
+}): Promise<StaticPathsResult>;