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/web_probe.gd

@@ -5,7 +5,7 @@ extends Node3D
 ## skinned mesh draws under a given engine build.
 
 func _ready() -> void:
-	var bull := (load("res://Assets/bull.fbx") as PackedScene).instantiate() as Node3D
+	var bull := (load("res://art/characters/bull.fbx") as PackedScene).instantiate() as Node3D
 	bull.scale = Vector3(100.0, 100.0, 100.0)
 	add_child(bull)