Phones: add views, edit relationships, and a better Detail view

On a phone held upright

• "+" in the tab row adds a view: Graph, Relationship, Slide or Map. Slides and maps are view only on a phone (build them on a larger screen), and Map is available once a map has been built.
• A cleaner Relationship view: no legend, the key event is one line at the bottom, and the settings open from the ◂ ✎ button. Dragging and pinching now move only the view, not the page.
• Edit relationships: atlas details and the event edit form now have a Relationships section, where you can add, edit and delete relationships. The relationship editor opens as a sheet with Done and Delete.
• Playback bar: new buttons to go back to the beginning and to repeat playback.
• Back to the phone layout: after Switch to desktop view, the rotate screen now has a Use phone layout button.

Everywhere

• Detail view: shows relationships again, clicking a card opens the event inspector, and dates follow your Year / Month / Day setting. On a computer, drag the ⠿ handle on a column to reorder columns; the order is saved with the project. The eye button hides collapsed columns.
• Relationship view: panning and zooming are smoother.
• Deleting an atlas now lists the relationships it affects before you confirm, then removes them cleanly.