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/lodash/_setToArray.js

@@ -0,0 +1,18 @@
+/**
+ * Converts `set` to an array of its values.
+ *
+ * @private
+ * @param {Object} set The set to convert.
+ * @returns {Array} Returns the values.
+ */
+function setToArray(set) {
+  var index = -1,
+      result = Array(set.size);
+
+  set.forEach(function(value) {
+    result[++index] = value;
+  });
+  return result;
+}
+
+module.exports = setToArray;