[Bug]: Dragging a note from the sidebar when a board is open lags the editor out significantly

[blubbers122]

Describe the bug

This is especially noticable with a board with several lists and items. Mine has 400+ items and 10ish lists.
New to this codebase, but my first guess is this is a performance issue with calculating the potential list insertion point in the case of the user placing the note from the sidebar into a list to create a new item. It might need spatial partitioning if the issue is what I think it is.

Expected Behavior

The editor should be responsive and shouldn't slow down to < 10fps :)

Steps to reproduce

1. Open a kanban board with several items (several hundred to really notice performance issue)
2. open the left sidebar (Files)
3. drag a file from the sidebar over the kanban board screen area
4. observe obsidian responsiveness

Relevant errors (if available)

Operating system

Windows

[blubbers122]

Yeah I see the code right here just loops through all list items for each update in the drag
https://github.com/obsidian-community/obsidian-kanban/blob/main/src/dnd/managers/DragManager.ts#L180

with a spatial partition structure, we can only check the relevant items for intersection, which I predict would reduce the loop iterations to about a max of 20. and go from O(n) -> O(1)