How to prevent grid size from expanding when dragging an item outside of its current dimensions?

**Test case:** https://packery.metafizzy.co/

In the demo you can keep growing the grid height as long as you keep stacking items on top of each other. I want to prevent this and only allow them to be dragged and dropped within the available space.

Reproduce the behavior in the Packery demo at https://packery.metafizzy.co/ by repeatedly stacking items outside the current grid dimensions. Start by tracing the drag-and-drop handling that expands the grid. Done means items can be dragged only within the available space and the grid no longer grows from out-of-bounds drops.

Written by the indexing model from the issue text.