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/reusify/reusify.d.ts

@@ -0,0 +1,14 @@
+interface Node {
+	next: Node | null;
+}
+
+interface Constructor<T> {
+	new(): T;
+}
+
+declare function reusify<T extends Node>(constructor: Constructor<T>): {
+	get(): T;
+	release(node: T): void;
+};
+
+export = reusify;