add audio_manager and code refactoring

core/ai/framework/state_machine.gd

@@ -0,0 +1,46 @@
+extends Node
+
+class_name StateMachine
+
+@export var initial_state: State
+
+var current_state: State
+var states: Dictionary = {}
+var enable: bool = true:
+	set(value):
+		enable = value
+		toggle_enable()
+
+func toggle_enable() -> void:
+	if !enable:
+		return
+	
+	if !states.is_empty():
+		return
+
+	for state in get_children():
+		if state is State:
+			states[state.state_id] = state
+			state.transitioned.connect(_on_state_transition)
+	
+	if initial_state:
+		current_state = initial_state
+		current_state.enter()
+
+func physics_process(delta) -> void:
+	if current_state and enable:
+		current_state.update(delta)
+
+func _on_state_transition(state: State, new_state_id: String) -> void:
+	if state != current_state:
+		return
+
+	var new_state = states.get(new_state_id)
+	if not new_state:
+		return
+
+	if current_state:
+		current_state.exit()
+	
+	current_state = new_state
+	current_state.enter()