The recursive RenderNode rendered every row of an expanded device, and built a
fresh context-menu list + closures per node per render. RawTreeRows flattens the
expanded tree (explicit stack) into rows rendered by one Virtualize; each level
shows 500 children, then a 'Show more' row. RawNodeMenuCache keys menus weakly
on the node instance and rebuilds on a picker-mode or Enabled change.
Refs #745
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Joseph Doherty