Adds the following fields to the WorkItem struct, sourced from the
corresponding GraphQL widgets:

- Color
- Confidential
- DueDate / StartDate (from the startAndDueDate widget)
- HealthStatus
- IterationID
- Labels
- LinkedItems
- MilestoneID
- ParentID
- Status (changed from string to *string, since the widget may be absent)
- Weight

The `workItemFeaturesGQL` struct is refactored from a flat, ad-hoc
structure into individual typed widget structs (one per widget), each
with its own nil-safe unwrap() method. This matches the shape of the
GraphQL API, where each widget is an independent nullable object, and
makes it straightforward to add further widgets in the future.

Two smaller fixes are included:

- userCoreBasicGQL.unwrap() now has a pointer receiver and handles
  nil, preventing a panic when the author field is absent on a work
  item.

- The Locked field is removed from the BasicUser populated via
  userCoreBasicGQL, as the GraphQL type does not expose a locked
  field; the previous derivation from state != "active" was
  incorrect.

With the new `WorkItemIID` type, the calling code will use this field as
`workitem.Parent.IID` – having the ID suffix in `ParentID` is unnecessary and
confusing.

Also change the slice of pointers to a slice of structs. Since slices can
themselves be nil, there is no need for the extra indirection.

feat(workitems): Add more fields to WorkItem

See merge request !2795

Changelog: Improvements

Implement body preserver to enable HTTP response body streaming

Closes #2134

See merge request !2746

## 2.1.0

### 🚀 Features

- feat(workitems): Add more fields to WorkItem ([!2795](!2795)) by [Florian Forster](https://gitlab.com/fforster)

### 🔄 Other Changes

- Implement body preserver to enable HTTP response body streaming ([!2746](!2746)) by [Timo Furrer](https://gitlab.com/timofurrer)

# [2.1.0](https://gitlab.com/gitlab-org/api/client-go/compare/v2.0.0...v2.1.0) (2026-03-03)

### Features

* **workitems:** Add more fields to WorkItem ([7088f6f2](7088f6f2))