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-value-parser/lib/stringify.js

@@ -0,0 +1,48 @@
+function stringifyNode(node, custom) {
+  var type = node.type;
+  var value = node.value;
+  var buf;
+  var customResult;
+
+  if (custom && (customResult = custom(node)) !== undefined) {
+    return customResult;
+  } else if (type === "word" || type === "space") {
+    return value;
+  } else if (type === "string") {
+    buf = node.quote || "";
+    return buf + value + (node.unclosed ? "" : buf);
+  } else if (type === "comment") {
+    return "/*" + value + (node.unclosed ? "" : "*/");
+  } else if (type === "div") {
+    return (node.before || "") + value + (node.after || "");
+  } else if (Array.isArray(node.nodes)) {
+    buf = stringify(node.nodes, custom);
+    if (type !== "function") {
+      return buf;
+    }
+    return (
+      value +
+      "(" +
+      (node.before || "") +
+      buf +
+      (node.after || "") +
+      (node.unclosed ? "" : ")")
+    );
+  }
+  return value;
+}
+
+function stringify(nodes, custom) {
+  var result, i;
+
+  if (Array.isArray(nodes)) {
+    result = "";
+    for (i = nodes.length - 1; ~i; i -= 1) {
+      result = stringifyNode(nodes[i], custom) + result;
+    }
+    return result;
+  }
+  return stringifyNode(nodes, custom);
+}
+
+module.exports = stringify;