fix(frontend): unify local settings runtime state and remove sidebar layout from LocalSettings (#1879)

* fix(frontend): resolve layout flickering by migrating workspace sidebar state to cookie

* fix(frontend): unify local settings runtime state to fix state drift

* fix(frontend): only persist thread model on explicit context model updates

frontend/src/components/query-client-provider.tsx

@@ -0,0 +1,20 @@
+"use client";
+
+import {
+  QueryClient,
+  QueryClientProvider as TanStackQueryClientProvider,
+} from "@tanstack/react-query";
+
+const queryClient = new QueryClient();
+
+export function QueryClientProvider({
+  children,
+}: Readonly<{
+  children: React.ReactNode;
+}>) {
+  return (
+    <TanStackQueryClientProvider client={queryClient}>
+      {children}
+    </TanStackQueryClientProvider>
+  );
+}