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/styled-jsx/css.d.ts

@@ -0,0 +1,18 @@
+// Definitions by: @types/styled-jsx <https://www.npmjs.com/package/@types/styled-jsx>
+
+declare module 'styled-jsx/css' {
+  import type { JSX } from "react";
+
+  function css(chunks: TemplateStringsArray, ...args: any[]): JSX.Element
+  namespace css {
+    export function global(
+      chunks: TemplateStringsArray,
+      ...args: any[]
+    ): JSX.Element
+    export function resolve(
+      chunks: TemplateStringsArray,
+      ...args: any[]
+    ): { className: string; styles: JSX.Element }
+  }
+  export = css
+}