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/toPrimitive.js

@@ -0,0 +1,12 @@
+var _typeof = require("./typeof.js")["default"];
+function toPrimitive(t, r) {
+  if ("object" != _typeof(t) || !t) return t;
+  var e = t[Symbol.toPrimitive];
+  if (void 0 !== e) {
+    var i = e.call(t, r || "default");
+    if ("object" != _typeof(i)) return i;
+    throw new TypeError("@@toPrimitive must return a primitive value.");
+  }
+  return ("string" === r ? String : Number)(t);
+}
+module.exports = toPrimitive, module.exports.__esModule = true, module.exports["default"] = module.exports;