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/egyptian.js

@@ -0,0 +1,24 @@
+/*
+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.
+*/
+const Fraction = require('fraction.js');
+
+// Based on http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fractions/egyptian.html
+function egyptian(a, b) {
+
+  var res = [];
+
+  do {
+    var t = Math.ceil(b / a);
+    var x = new Fraction(a, b).sub(1, t);
+    res.push(t);
+    a = Number(x.n);
+    b = Number(x.d);
+  } while (a !== 0n);
+  return res;
+}
+console.log("1 / " + egyptian(521, 1050).join(" + 1 / "));