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/webpack/cache-invalidation.d.ts

@@ -0,0 +1,17 @@
+/**
+ * Atomically write an invalidation marker.
+ *
+ * Because attempting to delete currently open cache files could cause issues,
+ * actual deletion of files is deferred until the next start-up (in
+ * `checkFileSystemCacheInvalidationAndCleanup`).
+ *
+ * In the case that no database is currently open (e.g. via a separate CLI
+ * subcommand), you should call `cleanupFileSystemCache` *after* this to eagerly
+ * remove the cache files.
+ */
+export declare function invalidateFileSystemCache(cacheDirectory: string): Promise<void>;
+/**
+ * Called during startup. See if the cache is in a partially-completed
+ * invalidation state. Finds and delete any invalidated cache files.
+ */
+export declare function checkFileSystemCacheInvalidationAndCleanup(cacheDirectory: string): Promise<void>;