Objective

Fix a regression in Neo.grid.Body where changing a column's dataField at runtime (e.g., toggling between Total/Public/Private stats) desynchronizes the columnPositions map and Row recycling logic, causing rendering artifacts during horizontal scrolling.

Root Cause Analysis

1. Stale columnPositions keys: The GridBody maintains a columnPositions collection keyed by dataField. When dataField changes on the column, the map key remains the old name, breaking lookups during updateMountedAndVisibleColumns.
2. Stale oldCellMap keys: In Neo.grid.Row, the recycling logic uses oldCellMap keyed by dataField to find reusable DOM nodes. If the column's dataField changes but the VDOM nodes still have the old data-field attribute, recycling fails or misidentifies cells.

Tasks

1. Sync columnPositions: Ensure that when a Column's dataField is updated, the GridBody's columnPositions map is updated to reflect the new key.
2. Robust Recycling: Verify Row recycling logic can handle dataField transitions, possibly by forcing a full re-render (non-recycled) when column definitions change significantly.
3. Verification: Verify that horizontal scrolling works seamlessly after a Data Mode switch in DevIndex.