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_boss_test.gd

@@ -67,11 +67,11 @@ func _make_floor() -> StaticBody3D:
 func _run() -> void:
 	root.add_child(_make_floor())
 
-	_bull = (load("res://Player.tscn") as PackedScene).instantiate()
+	_bull = (load("res://actors/player/player.tscn") as PackedScene).instantiate()
 	root.add_child(_bull)
 	_bull.global_position = Vector3(4, 1, 0)
 
-	_bear = (load("res://Bear.tscn") as PackedScene).instantiate()
+	_bear = (load("res://actors/bear/bear.tscn") as PackedScene).instantiate()
 	root.add_child(_bear)
 	_bear.global_position = Vector3(0, 1, 0)
 	await physics_frame