新增实体对话功能，支持指定任意实体作为对话的说话者，指令格式更新为 /dialog show <dialog_id> ，同时保持向后兼容性。对话中的指令将以指定实体身份执行，未指定时默认为玩家本身。

Added entity dialog feature that supports specifying any entity as the dialog speaker, with updated command format /dialog show <dialog_id> while maintaining backward compatibility. Commands in dialogs will execute with the specified entity's identity, defaulting to the player when no entity is specified.