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/@heroicons/react/20/solid/BookOpenIcon.js

@@ -0,0 +1,22 @@
+const React = require("react");
+function BookOpenIcon({
+  title,
+  titleId,
+  ...props
+}, svgRef) {
+  return /*#__PURE__*/React.createElement("svg", Object.assign({
+    xmlns: "http://www.w3.org/2000/svg",
+    viewBox: "0 0 20 20",
+    fill: "currentColor",
+    "aria-hidden": "true",
+    "data-slot": "icon",
+    ref: svgRef,
+    "aria-labelledby": titleId
+  }, props), title ? /*#__PURE__*/React.createElement("title", {
+    id: titleId
+  }, title) : null, /*#__PURE__*/React.createElement("path", {
+    d: "M10.75 16.82A7.462 7.462 0 0 1 15 15.5c.71 0 1.396.098 2.046.282A.75.75 0 0 0 18 15.06v-11a.75.75 0 0 0-.546-.721A9.006 9.006 0 0 0 15 3a8.963 8.963 0 0 0-4.25 1.065V16.82ZM9.25 4.065A8.963 8.963 0 0 0 5 3c-.85 0-1.673.118-2.454.339A.75.75 0 0 0 2 4.06v11a.75.75 0 0 0 .954.721A7.506 7.506 0 0 1 5 15.5c1.579 0 3.042.487 4.25 1.32V4.065Z"
+  }));
+}
+const ForwardRef = /*#__PURE__*/ React.forwardRef(BookOpenIcon);
+module.exports = ForwardRef;