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/utils/clone.cjs

@@ -0,0 +1,25 @@
+'use strict';
+
+const List = require('./List.cjs');
+
+function clone(node) {
+    const result = {};
+
+    for (const key in node) {
+        let value = node[key];
+
+        if (value) {
+            if (Array.isArray(value) || value instanceof List.List) {
+                value = value.map(clone);
+            } else if (value.constructor === Object) {
+                value = clone(value);
+            }
+        }
+
+        result[key] = value;
+    }
+
+    return result;
+}
+
+exports.clone = clone;