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/@babel/runtime/helpers/esm/objectWithoutProperties.js

@@ -0,0 +1,13 @@
+import objectWithoutPropertiesLoose from "./objectWithoutPropertiesLoose.js";
+function _objectWithoutProperties(e, t) {
+  if (null == e) return {};
+  var o,
+    r,
+    i = objectWithoutPropertiesLoose(e, t);
+  if (Object.getOwnPropertySymbols) {
+    var n = Object.getOwnPropertySymbols(e);
+    for (r = 0; r < n.length; r++) o = n[r], -1 === t.indexOf(o) && {}.propertyIsEnumerable.call(e, o) && (i[o] = e[o]);
+  }
+  return i;
+}
+export { _objectWithoutProperties as default };