Is it permissible to marry for the sake of chastity while possessing sufficient funds for the expenses of marriage and sustenance for a year or more, but without currently having a job or a stable income?

You are permitted to proceed with marriage; in fact, initiating it is required of you. There is no infringement on the wife's rights in this, for Ibn Qudamah said: "The apparent meaning of Ahmad's words is that there is no difference between one who is able to spend [on his wife] and one who is unable." He supported this by citing that the Prophet, peace and blessings be upon him, married a man who could only afford an iron ring. So, proceed with marriage and rely upon Allah, the Exalted.