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/parse.d.ts

@@ -0,0 +1,9 @@
+import { Parser } from './postcss.js'
+
+interface Parse extends Parser {
+  default: Parse
+}
+
+declare let parse: Parse
+
+export = parse