* Menu item "Sprint planning"

* Begin of the insertion~~AddEnd of the insertion Begin of the deletion AddEnd of the deletion subheader (suggestion from Alex: use the subheader filter slot for the Begin of the insertionbuttons)~~End of the insertion Begin of the deletion buttons)End of the deletion

* Select the displayed backlog via a single-select `SelectPanel` -> synchronous implementation will suffice as a first step.

* Introduce `+ Sprint` button, there will no longer be a `+ Version` button

* Begin of the insertion~~AboutEnd of the insertion Begin of the deletion AboutEnd of the deletion splitting the view: consult Begin of the insertionHenriette~~End of the insertion Begin of the deletion HenrietteEnd of the deletion

* \[nice to have\] Make panes resizable Begin of the insertion(would need to port component from Angular)End of the insertion

* Introduce a separate component for the `BacklogPane`

* Consider how to represent the view as a URL

* When you open the details view for a Work Package: keep the current responsive behavior, details to the right.