- Add @apollo/client ^4.1.9 and graphql ^16.10.0 dependencies to package.json
- Add apollo-client.ts with ApolloClient configuration, HTTP link to API server, and auth link for token-based authentication
- Add Providers component wrapping children with ApolloProvider
- Wrap Sidebar and main content with Providers in root layout
- Configure cache-and-network and network-only fetch policies for queries and mutations