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/axios/lib/helpers/spread.js

@@ -0,0 +1,28 @@
+'use strict';
+
+/**
+ * Syntactic sugar for invoking a function and expanding an array for arguments.
+ *
+ * Common use case would be to use `Function.prototype.apply`.
+ *
+ *  ```js
+ *  function f(x, y, z) {}
+ *  const args = [1, 2, 3];
+ *  f.apply(null, args);
+ *  ```
+ *
+ * With `spread` this example can be re-written.
+ *
+ *  ```js
+ *  spread(function(x, y, z) {})([1, 2, 3]);
+ *  ```
+ *
+ * @param {Function} callback
+ *
+ * @returns {Function}
+ */
+export default function spread(callback) {
+  return function wrap(arr) {
+    return callback.apply(null, arr);
+  };
+}