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/has-property-descriptors/index.js

@@ -0,0 +1,22 @@
+'use strict';
+
+var $defineProperty = require('es-define-property');
+
+var hasPropertyDescriptors = function hasPropertyDescriptors() {
+	return !!$defineProperty;
+};
+
+hasPropertyDescriptors.hasArrayLengthDefineBug = function hasArrayLengthDefineBug() {
+	// node v0.6 has a bug where array lengths can be Set but not Defined
+	if (!$defineProperty) {
+		return null;
+	}
+	try {
+		return $defineProperty([], 'length', { value: 1 }).length !== 1;
+	} catch (e) {
+		// In Firefox 4-22, defining length on an array throws an exception.
+		return true;
+	}
+};
+
+module.exports = hasPropertyDescriptors;