feat(frontend): add API client, layout, and routing

- Create Axios-based API client with sources, jobs, and dashboard endpoints
- Add responsive Layout component with navigation sidebar
- Set up React Router with Dashboard, Backups, and Settings routes
- Configure TanStack Query provider with default options
- Use lucide-react for navigation icons

frontend/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;