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/postcss/lib/parse.d.ts

@@ -0,0 +1,9 @@
+import { Parser } from './postcss.js'
+
+interface Parse extends Parser {
+  default: Parse
+}
+
+declare const parse: Parse
+
+export = parse