Uses `classed` on enter nodes instead of overriding classes.
Uses `classed` on enter nodes instead of overriding classes.

This is needed when incoming nodes (from an expand) are set to
`movable`. When enter is called, it was overwriting the classes.

For https://github.com/SpiderStrategies/Scoreboard/issues/14263

SpiderStrategies/kalpa-tree,SpiderStrategies/kalpa-tree