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/css-tree/cjs/syntax/config/walker.cjs

@@ -0,0 +1,9 @@
+'use strict';
+
+const index = require('../node/index.cjs');
+
+const config = {
+    node: index
+};
+
+module.exports = config;