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/gray-matter/lib/engine.js

@@ -0,0 +1,30 @@
+'use strict';
+
+module.exports = function(name, options) {
+  let engine = options.engines[name] || options.engines[aliase(name)];
+  if (typeof engine === 'undefined') {
+    throw new Error('gray-matter engine "' + name + '" is not registered');
+  }
+  if (typeof engine === 'function') {
+    engine = { parse: engine };
+  }
+  return engine;
+};
+
+function aliase(name) {
+  switch (name.toLowerCase()) {
+    case 'js':
+    case 'javascript':
+      return 'javascript';
+    case 'coffee':
+    case 'coffeescript':
+    case 'cson':
+      return 'coffee';
+    case 'yaml':
+    case 'yml':
+      return 'yaml';
+    default: {
+      return name;
+    }
+  }
+}