- chain rows lose the WaypointsIcon (owner: not needed — the chips +
connectors already read as chains); folders keep their icons.
- THE ALIGNMENT STAIRCASE: every level's checkbox sits directly under
its parent's expander arrow. The expander now shares the checkbox's
14px width (h-5 w-3.5), making each nesting step exactly 18px —
clusters pl-3 (12px) → chains pl-7.5 (30px, the cluster expander) →
statements pl-12 (48px, the chain expander). Live-measured: 318=318,
336=336.