docs(design): remove SVG, use PNG logo only

SVG icon is no longer in use. public/logo.png (1024x1024 RGBA) is
the single logo asset. DESIGN.md updated accordingly: SVG snippet
removed, wordmark pattern and <head> references updated to PNG.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

node_modules/postcss/lib/comment.js

@@ -0,0 +1,13 @@
+'use strict'
+
+let Node = require('./node')
+
+class Comment extends Node {
+  constructor(defaults) {
+    super(defaults)
+    this.type = 'comment'
+  }
+}
+
+module.exports = Comment
+Comment.default = Comment