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/defineProperty.js

@@ -0,0 +1,10 @@
+var toPropertyKey = require("./toPropertyKey.js");
+function _defineProperty(e, r, t) {
+  return (r = toPropertyKey(r)) in e ? Object.defineProperty(e, r, {
+    value: t,
+    enumerable: !0,
+    configurable: !0,
+    writable: !0
+  }) : e[r] = t, e;
+}
+module.exports = _defineProperty, module.exports.__esModule = true, module.exports["default"] = module.exports;