Idle frames tick on a global clock offset by entity id, walk frames run
on a per-entity clock while the position lerp is in flight, and the sim's
Attacked/Died events drive the attacker's action, the victim's flinch and
a corpse that shows the dead frames for a few seconds. All render-side;
the sim is untouched. The snapshot test can dump a strip of frames.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>