Currently, Neo.grid.column.Base does not support a cellCls config. Developers must return an object {html, cls} from the renderer to apply dynamic classes, which mixes content and styling logic.

To support cleaner code (as seen in apps/devrank), implement cellCls in Neo.grid.column.Base and update Neo.grid.Row to apply it.

1. Add cellCls config to src/grid/column/Base.mjs.
2. Update src/grid/Row.mjs applyRendererOutput to resolve column.cellCls (supporting Function, String, or Array) and append to the cell classes.