Fix drag-and-drop memory leak and reordering with variable item heights

[AustinMKerr]

Summary

Fixes two issues in the dynamic item-height drag-and-drop path that were introduced alongside the itemsHeightArray refactor.

1. Memory leak during drag

computeItemHeightArray() called console.log({ itemHeights }) (and console.log("Document not found")) every time it ran — and it runs on every dragover event, which fires continuously while dragging. Objects passed to console.log are retained by the browser's console heap and can never be garbage-collected, so memory grew unbounded for the duration of each drag (and it spammed the console / added work on a hot path).

Fix: removed the hot-path logging. The function now just measures and returns the heights.

2. Reordering doesn't track when nodes are different sizes

The cumulative-height loop in getHoveringPosition only assigned linearIndex / hoveringPosition when the pointer landed inside an item's vertical range. When the pointer was below the last item (e.g. dragging into the empty space at the bottom of the tree), the loop never matched, so both values stayed 0 and the drop indicator snapped to the top of the tree. linearIndex was also derived directly from the (possibly out-of-range) loop index rather than being clamped against the real linear-item list.

Fix: rewrote the calculation to

• compute a fractional "linear index" from each item's measured height (integer part = item index, fractional part = how far into that item the pointer is), so tracking is correct regardless of differing node sizes;
• treat "pointer below the last item" as past-the-end, so the existing bottom-drop detection resolves to a bottom offset;
• clamp linearIndex to the actual linearItems range, matching the original robust behavior.

Also removed dead commented-out code left over from the WIP.

Notes

• DragBetweenLine already positions the indicator by summing per-item heights, so it stays consistent with the corrected linearIndex.
• No API changes; itemHeight / itemsHeightArray context fields are unchanged.

Testing

Type/logic reviewed locally. A full tsc/jest run wasn't possible in this environment because node_modules isn't installed (dependency resolution errors are unrelated to these changes).

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