Swastika is Auspicious symbol for Hindus. I have only heard about the significance of Swastika no solid proof from Shastras. Where is swastika mentioned in Yagna Rituals specifically Yajurveda if it is/was ever used in Yagnas. If it has some puranic importance where is it mentioned in puranas.
There is a saying that Swastika symbol is specifically used for worshiping Ganesha.