Help users getting started with schedules

[nilmerg]

Users seem to struggle to…

• …notice that there are multiple rotations possible
• …notice where to add the first rotation

Goal

As long as there are no rotations, the first row should have no title and no grid and have a grey background. The message previously in the title must be moved to the center of the row. In addition to that, the button to add a rotation (currently located at the top right) must be moved beside it.

Once a rotation has been added, there should always be a row with the same gray background at the bottom, right before the result. The button to add a rotation is then visible there in its center.

Mockups for this are in the parent issue.