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/autoprefixer/lib/hacks/border-image.js

@@ -0,0 +1,15 @@
+let Declaration = require('../declaration')
+
+class BorderImage extends Declaration {
+  /**
+   * Remove fill parameter for prefixed declarations
+   */
+  set(decl, prefix) {
+    decl.value = decl.value.replace(/\s+fill(\s)/, '$1')
+    return super.set(decl, prefix)
+  }
+}
+
+BorderImage.names = ['border-image']
+
+module.exports = BorderImage