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/recharts/lib/util/ShallowEqual.js

@@ -0,0 +1,20 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.shallowEqual = shallowEqual;
+function shallowEqual(a, b) {
+  /* eslint-disable no-restricted-syntax */
+  for (var key in a) {
+    if ({}.hasOwnProperty.call(a, key) && (!{}.hasOwnProperty.call(b, key) || a[key] !== b[key])) {
+      return false;
+    }
+  }
+  for (var _key in b) {
+    if ({}.hasOwnProperty.call(b, _key) && !{}.hasOwnProperty.call(a, _key)) {
+      return false;
+    }
+  }
+  return true;
+}