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/bear_hitbox_test.gd

@@ -52,7 +52,7 @@ func _drive(bear: Node, fire: String) -> void:
 
 
 func _run() -> void:
-	var bear := (load("res://Bear.tscn") as PackedScene).instantiate() as Node3D
+	var bear := (load("res://actors/bear/bear.tscn") as PackedScene).instantiate() as Node3D
 	root.add_child(bear)
 	bear.set_physics_process(false)   # freeze the AI; we fire the colliders ourselves
 	await physics_frame