HitZonesTrait
constHitZonesTrait:Trait<() =>HitZone[]>
The zones a shot may strike on the entity, in its own frame. A ray
that meets a zone hits the entity even where it passes outside its
body, and the nearest zone it meets names the hit: a head declared in
one line is HitZones([{ name: "head", multiplier: 2, at: { x: 0, y: 1.5, z: 0 }, radius: 0.25 }]). The stream carries it, so every page tests the same
shapes as the room.