8. GraphQL Server Setup

- [x] 8.1 Implement `graphql/server.go`
  - NewServer(resolver) function
  - Configure GraphQL handler
  - Configure GraphQL Playground (development only)
  - Error logging
- [x] 8.2 Add server configuration
  - Port configuration (environment variable, default 8080)
  - CORS configuration
  - Request logging

Source: openspec/changes/bootstrap-mvp-foundation/tasks.md