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/fraction.js/examples/valueOfPi.js

@@ -0,0 +1,42 @@
+/*
+Fraction.js v5.0.0 10/1/2024
+https://raw.org/article/rational-numbers-in-javascript/
+
+Copyright (c) 2024, Robert Eisele (https://raw.org/)
+Licensed under the MIT license.
+*/
+
+var Fraction = require("fraction.js")
+
+function valueOfPi(val) {
+
+  let minLen = Infinity, minI = 0, min = null;
+  const choose = [val, val * Math.PI, val / Math.PI];
+  for (let i = 0; i < choose.length; i++) {
+    let el = new Fraction(choose[i]).simplify(1e-13);
+    let len = Math.log(Number(el.n) + 1) + Math.log(Number(el.d));
+    if (len < minLen) {
+      minLen = len;
+      minI = i;
+      min = el;
+    }
+  }
+
+  if (minI == 2) {
+    return min.toFraction().replace(/(\d+)(\/\d+)?/, (_, p, q) =>
+      (p == "1" ? "" : p) + "π" + (q || ""));
+  }
+
+  if (minI == 1) {
+    return min.toFraction().replace(/(\d+)(\/\d+)?/, (_, p, q) =>
+      p + (!q ? "/π" : "/(" + q.slice(1) + "π)"));
+  }
+  return min.toFraction();
+}
+
+console.log(valueOfPi(-3)); // -3
+console.log(valueOfPi(4 * Math.PI)); // 4π
+console.log(valueOfPi(3.14)); // 157/50
+console.log(valueOfPi(3 / 2 * Math.PI)); // 3π/2
+console.log(valueOfPi(Math.PI / 2)); // π/2
+console.log(valueOfPi(-1 / (2 * Math.PI))); // -1/(2π)