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/touch_controls_test.gd

@@ -73,7 +73,7 @@ func _run() -> void:
 	# Headless boots a 64x64 root viewport, which collapses every UI rect on top of each other.
 	# Give it a real phone-ish landscape size so the joystick zone / buttons lay out sanely.
 	root.size = Vector2i(1152, 648)
-	_tc = (load("res://touch_controls.gd") as Script).new()
+	_tc = (load("res://systems/input/touch_controls.gd") as Script).new()
 	root.add_child(_tc)
 	await process_frame   # _ready builds _surface and runs the first _relayout
 	_tc._relayout()       # ensure the layout reflects the size set above