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/postcss/lib/warning.js

@@ -0,0 +1,37 @@
+'use strict'
+
+class Warning {
+  constructor(text, opts = {}) {
+    this.type = 'warning'
+    this.text = text
+
+    if (opts.node && opts.node.source) {
+      let range = opts.node.rangeBy(opts)
+      this.line = range.start.line
+      this.column = range.start.column
+      this.endLine = range.end.line
+      this.endColumn = range.end.column
+    }
+
+    for (let opt in opts) this[opt] = opts[opt]
+  }
+
+  toString() {
+    if (this.node) {
+      return this.node.error(this.text, {
+        index: this.index,
+        plugin: this.plugin,
+        word: this.word
+      }).message
+    }
+
+    if (this.plugin) {
+      return this.plugin + ': ' + this.text
+    }
+
+    return this.text
+  }
+}
+
+module.exports = Warning
+Warning.default = Warning