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/es-get-iterator/node.mjs

@@ -0,0 +1,11 @@
+// this should only run in node >= 13.7, so it
+// does not need any of the intense fallbacks that old node/browsers do
+
+var $iterator = Symbol.iterator;
+
+export default function getIterator(iterable) {
+	// alternatively, `iterable[$iterator]?.()`
+	if (iterable != null && iterable[$iterator] !== undefined) {
+		return iterable[$iterator]();
+	}
+}