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/autoprefixer/lib/hacks/placeholder-shown.js

@@ -0,0 +1,19 @@
+let Selector = require('../selector')
+
+class PlaceholderShown extends Selector {
+  /**
+   * Return different selectors depend on prefix
+   */
+  prefixed(prefix) {
+    if (prefix === '-moz-') {
+      return ':-moz-placeholder'
+    } else if (prefix === '-ms-') {
+      return ':-ms-input-placeholder'
+    }
+    return `:${prefix}placeholder-shown`
+  }
+}
+
+PlaceholderShown.names = [':placeholder-shown']
+
+module.exports = PlaceholderShown