<img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/920682/content">

Rework the component structure Begin of the insertionbasedEnd of the insertion Begin of the deletion baseEnd of the deletion on the wireframe Begin of the insertionabove.End of the insertion Begin of the deletion aboveEnd of the deletion

Begin of the insertionNote: the wireframe annotation naming has drifted relative to the current code and planned implementation. In particular, this PR series is not introducing a separate `BucketsComponent`; the future `BacklogComponent` is still expected to own the backlog header, bucket-list composition, and inbox composition. Claude Design is currently unavailable, so the diagram itself has not yet been updated.

Maintenance checklist:

- [x] Create `WorkPackageCardBoxComponent`
- [x] Create `WorkPackageCardComponent`
- [x] Wire up `SprintComponent` to use `WorkPackageCardBoxComponent` (implementation to validate `WorkPackageCardBox` API)
- [x] Rename `BacklogBuckets*Component` to `BucketComponent` (replaces #22886)
- [x] Rename `New*Component`/`New*Form` to `*Component`/`*Form`
- [x] Rename `BacklogsComponent` to `BacklogComponent` and keep ownership of the backlog header, bucket-list composition, and inbox composition
- [ ] Extract `SprintsComponent` from `backlog/_backlog_list.html.erb`
- [x] Wire up `BucketComponent` to use `WorkPackageCardBoxComponent`
- [ ] Wire up `InboxComponent` to use `WorkPackageCardBoxComponent`
- [ ] Extract a polymorphic container adapter for shared card primitivesEnd of the insertion Begin of the deletion <br>End of the deletion