click an asset then the floor, or drag it in · click to select, then
drag to move, a gizmo arm for one axis, the ring to turn · ctrl (cmd)
= free geometry: click a dot for a vertex then drag its arms, a small dot to
push or pull the whole wall, shift-click to split · the two wall modes
are at the top of the browser (g, p)
every other key is a button under Shortcuts, with its key on it