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/difficulty_sim.gd

@@ -49,9 +49,9 @@ func _init() -> void:
 func _run() -> void:
 	_dt = 1.0 / float(Engine.physics_ticks_per_second)
 	_dp = root.get_node_or_null("/root/DP")
-	_mat_scene = load("res://Matador.tscn") as PackedScene
+	_mat_scene = load("res://actors/matador/matador.tscn") as PackedScene
 
-	_scene = (load("res://scene.tscn") as PackedScene).instantiate()
+	_scene = (load("res://levels/game_shell.tscn") as PackedScene).instantiate()
 	root.add_child(_scene)
 	current_scene = _scene
 	await create_timer(0.5).timeout