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/is-thenable.d.ts

@@ -0,0 +1,7 @@
+/**
+ * Check to see if a value is Thenable.
+ *
+ * @param promise the maybe-thenable value
+ * @returns true if the value is thenable
+ */
+export declare function isThenable<T = unknown>(promise: Promise<T> | T): promise is Promise<T>;