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>

matador_ragdoll.gd

@@ -4,6 +4,8 @@ extends RefCounted
 ## limited swing/twist (DP-tunable) so the corpse keeps its silhouette instead of
 ## folding into a flat "deflated" pile; the cape stays free (PIN) so it drapes.
 
+const PhysicsLayers = preload("res://physics_layers.gd")
+
 # [bone, radius] → sphere collider; [bone, radius, height] → capsule.
 const _BONES: Array = [
 	["matador",       0.18],
@@ -53,10 +55,15 @@ static func build(skeleton: Skeleton3D) -> PhysicalBoneSimulator3D:
 		pb.bone_name       = bname
 		pb.mass            = 0.4
 		pb.linear_damp     = 0.1
-		pb.collision_layer = 1
-		pb.collision_mask  = 1
+		# The ragdoll only simulates once the matador is dead, so it lives on the CORPSE
+		# layer and masks to CORPSE alone: it rests on the ground/walls (which also carry
+		# CORPSE) but the bull — which collides only with WORLD — passes straight through
+		# the bodies instead of tripping over them.
+		pb.collision_layer = PhysicsLayers.CORPSE
+		pb.collision_mask  = PhysicsLayers.CORPSE
 		if bname.begins_with("Bone"):
-			# Cape: floppy cloth — free swing, light, draggy, one-way collision.
+			# Cape: floppy cloth — free swing, light, draggy, one-way collision (layer 0
+			# so nothing collides with it; it still drapes on the CORPSE-masked ground).
 			pb.joint_type      = PhysicalBone3D.JOINT_TYPE_PIN
 			pb.mass            = 0.15
 			pb.linear_damp     = 0.5