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-js/sync.js

@@ -0,0 +1,12 @@
+let postcss = require('postcss')
+
+let parse = require('./parser')
+let processResult = require('./process-result')
+
+module.exports = function (plugins) {
+  let processor = postcss(plugins)
+  return input => {
+    let result = processor.process(input, { parser: parse, from: undefined })
+    return processResult(result)
+  }
+}