/// Interactive clip plane controller: position and orient section planes.
/// Transform gizmo (translate, rotate, scale) with hit testing.
/// Action-based input system with mode-sensitive key/mouse bindings.
/// Object manipulation controller (move, rotate, scale with constraints and numeric input).
/// Ray-cast object picking.
/// Multi-select system for viewport objects.
/// Transform snapping helpers and constraint overlay types.
/// Typed sub-object reference and sub-object selection set.