Create the backend project with a GraphQL server on port 3001. ## Tasks - [x] Create `backend/` as an npm workspace with TypeScript strict mode - [x] Add Apollo Server (we should agree on the dependency in the group first) - [x] Add ESLint and Prettier config, plus `dev` and `build` scripts - [x] Update "Start backend" and the folder structure in AGENTS.md ## Done when `npm run dev` starts a server that answers a test query on port 3001.