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/shared/lib/get-webpack-bundler.d.ts

@@ -0,0 +1,8 @@
+import { webpack } from 'next/dist/compiled/webpack/webpack';
+/**
+ * Depending on if Rspack is active or not, returns the appropriate set of
+ * webpack-compatible api.
+ *
+ * @returns webpack bundler
+ */
+export default function getWebpackBundler(): typeof webpack;