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/resolve/lib/core.js

@@ -0,0 +1,12 @@
+'use strict';
+
+var isCoreModule = require('is-core-module');
+var data = require('./core.json');
+
+var core = {};
+for (var mod in data) { // eslint-disable-line no-restricted-syntax
+    if (Object.prototype.hasOwnProperty.call(data, mod)) {
+        core[mod] = isCoreModule(mod);
+    }
+}
+module.exports = core;