Does sincere repentance permit a fornicator to marry someone else, and what is the evidence for this from the Quran and Sunnah? Is there a school of thought that prohibits the marriage of a fornicator (male or female) to someone else, even if they have repented?

It is not a prerequisite for repentance from zina (fornication/adultery) to have the hadd (prescribed punishment) inflicted upon the fornicator/adulterer. Whoever repents with sincere repentance, Allah accepts his repentance. The hadd atones for the sin of disobedience. Repentance, by the consensus of Muslims, abrogates the sin of major transgressions. Indeed, Ma'iz and Al-Ghamidiyyah insisted on confessing and chose stoning, because the attainment of absolution through hudud and the removal of sin is certain, unlike repentance, which may not be sincere or may have some of its conditions unfulfilled. If a person repents from zina, the description of zina is removed from him, and he is no longer included in the prohibition mentioned in the Almighty's saying: (The fornicator does not marry except a fornicatress or a polytheist...), due to the Prophet's (peace be upon him) saying: ("The one who repents from sin is like one who has no sin"). So, the penitent should not look to the past, for Allah accepts repentance no matter how great the sin, and it is permissible for him to marry a committed, chaste woman, and he must conceal himself and not inform anyone of his sin.