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/recharts/lib/component/Cell.js

@@ -0,0 +1,14 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.Cell = void 0;
+/**
+ * @fileOverview Cross
+ */
+
+var Cell = exports.Cell = function Cell(_props) {
+  return null;
+};
+Cell.displayName = 'Cell';