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/escalade/sync/index.js

@@ -0,0 +1,18 @@
+const { dirname, resolve } = require('path');
+const { readdirSync, statSync } = require('fs');
+
+module.exports = function (start, callback) {
+	let dir = resolve('.', start);
+	let tmp, stats = statSync(dir);
+
+	if (!stats.isDirectory()) {
+		dir = dirname(dir);
+	}
+
+	while (true) {
+		tmp = callback(dir, readdirSync(dir));
+		if (tmp) return resolve(dir, tmp);
+		dir = dirname(tmp = dir);
+		if (tmp === dir) break;
+	}
+}