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/defineAccessor.js

@@ -0,0 +1,8 @@
+function _defineAccessor(e, r, n, t) {
+  var c = {
+    configurable: !0,
+    enumerable: !0
+  };
+  return c[e] = t, Object.defineProperty(r, n, c);
+}
+module.exports = _defineAccessor, module.exports.__esModule = true, module.exports["default"] = module.exports;