/// 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).
/// Pick mask for controlling item types and sub-element levels in pick calls.
/// 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.
/// Interactive 3D probe and region widgets (line probe, sphere, box).