Put dead matadors on a corpse collision layer

A killed matador's ragdoll shared the WORLD layer with the bull, so the
bull collided with the bodies and spazzed out on them. Give corpses a
dedicated CORPSE layer masked to itself, and tag the ground/walls with
CORPSE too (at level load, so it also reaches colliders baked into the
instanced GLB arenas). The corpse still rests on the arena, but the bull
— which only masks WORLD — passes straight through the bodies.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

project.godot

@@ -118,6 +118,12 @@ ability_roll={
 
 pointing/emulate_touch_from_mouse=true
 
+[layer_names]
+
+3d_physics/layer_1="world"
+3d_physics/layer_2="bull"
+3d_physics/layer_3="corpse"
+
 [physics]
 
 3d/physics_engine="Jolt Physics"