test: load MovementStateMachine + state scripts via set_script() at runtime

Root cause: builder created plain Node instances for the state machine
and states, so _machine.player = self in PlayerMovementController
crashed with 'Invalid assignment ... on base object of type Node'.
Now each node gets its real script attached before _ready() runs.

debug/test_level_builder.gd

@@ -11,7 +11,6 @@ func build() -> void:
 	_build_walls()
 	_build_lighting()
 	_build_player()
-	_build_camera()
 	_build_ui()
 
 
@@ -65,35 +64,42 @@ func _build_player() -> void:
 	shape.shape.radius = 0.4
 	shape.shape.height = 1.8
 	player.add_child(shape)
+
+	# State machine
 	var sm := Node.new()
 	sm.name = "MovementStateMachine"
 	player.add_child(sm)
-	for state_name in ["ground", "air", "wall_run", "wall_cling", "slide", "dash"]:
+
+	var sm_script = load("res://movement/movement_state_machine.gd")
+	if sm_script:
+		sm.set_script(sm_script)
+
+	# State children
+	var state_scripts := {
+		"ground": "res://movement/states/state_ground.gd",
+		"air": "res://movement/states/state_air.gd",
+		"wall_run": "res://movement/states/state_wall_run.gd",
+		"wall_cling": "res://movement/states/state_wall_cling.gd",
+		"slide": "res://movement/states/state_slide.gd",
+		"dash": "res://movement/states/state_dash.gd",
+	}
+	for state_name in state_scripts:
 		var st := Node.new()
 		st.name = "state_" + state_name
 		sm.add_child(st)
+		var st_script = load(state_scripts[state_name])
+		if st_script:
+			st.set_script(st_script)
+
+	# Movement controller
 	var mover_script = load("res://movement/player_movement_controller.gd")
 	if mover_script:
 		player.set_script(mover_script)
-		# set_script after node is in tree does not auto-call _ready()
-		# Manually initialize the controller
+		# set_script does not auto-call _ready(); do it manually
 		if player.has_method("_ready"):
 			player._ready()
 
 
-func _build_camera() -> void:
-	var cam := Camera3D.new()
-	cam.name = "FpsCamera"
-	cam.current = true
-	cam.position = Vector3(0, 1.7, 0)
-	cam.fov = 90.0
-	var player_node = get_node_or_null("Player")
-	if player_node:
-		player_node.add_child(cam)
-	else:
-		add_child(cam)
-
-
 func _build_ui() -> void:
 	var canvas := CanvasLayer.new()
 	canvas.name = "UI"