The work items list page currently fetches data via two parallel GraphQL queries (`workItemsFull` + `workItemsSlim`) merged client side. This epic tracks the frontend work to fully migrate to the new REST API `GET /api/v4/namespaces/:id/-/work_items` as the sole data source. A POC MR validated the approach: a local Apollo resolver intercepts a GraphQL query, fetches from REST, and maps the response to the GraphQL shape. The POC runs REST alongside the full GraphQL query for field parity. This epic covers expanding the resolver to full parity so the GraphQL queries can be dropped. **Release** Enabling this feature relies on two flags (subject to change/update): * work_item_rest_api_frontend_users (to be user scoped) * work_item_rest_api