How can the two noble verses be reconciled: "It is not for the sun to overtake the moon" and "and the sun and the moon will be gathered"?

There is no contradiction between the two verses. The first verse pertains to this world, while the second verse pertains to the Day of Resurrection, as is clear from the name of the Sura (Al-Qiyamah - The Resurrection) and from the context. This is further indicated by what Al-Baghawi said: "{And the sun and the moon are gathered}" as two black, rolled-up entities, as if they were two slaughtered bulls. It was also said: they will be gathered in the sense of their light departing. And 'Ata bin Yasar said: They will be gathered on the Day of Resurrection, then cast into the sea, becoming the greater fire of Allah.