Reorganize into role-based folders and consolidate art

Move every script and scene into role-based directories (actors/, systems/, ui/,
levels/, props/) and all raw art under art/ (grouped by role, snake_case,
Extract-Textures GLBs), dropping Blender version-suffix noise. Filenames are
snake_case (PascalCase reserved for class_name) to avoid case-insensitive
filesystem aliasing on the web/macOS targets. Routes the bull's hits through the
typed DamageEvent pipeline and wires the bull's abilities to the Fx library.
Updates CLAUDE.md's folder-layout overview to match.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CCyaJPTHCH9EDthpf4A5Sj

tests/rigid_skin_test.gd

@@ -7,7 +7,7 @@ extends SceneTree
 ## hides the original skinned meshes (so they never hit the invisible-on-Mali skinning path).
 ## Run: godot --headless --script res://tests/rigid_skin_test.gd
 
-const RigidSkin = preload("res://rigid_skin.gd")
+const RigidSkin = preload("res://systems/render/rigid_skin.gd")
 
 var _pass := 0
 var _fail := 0
@@ -43,7 +43,7 @@ func _surface_mats(mi: MeshInstance3D) -> Array:
 
 
 func _run() -> void:
-	var inst: Node = (load("res://Assets/Matador.glb") as PackedScene).instantiate()
+	var inst: Node = (load("res://art/characters/matador.glb") as PackedScene).instantiate()
 	root.add_child(inst)
 
 	# Distinct materials on the skinned source meshes, before conversion.