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/object.assign/test/ses-compat.js

@@ -0,0 +1,12 @@
+'use strict';
+
+/* globals lockdown */
+
+// requiring ses exposes "lockdown" on the global
+require('ses');
+
+// lockdown freezes the primordials
+lockdown({ errorTaming: 'unsafe' });
+
+// initialize the module
+require('./');