What is the Sharia ruling on making up the Sunnah of Fajr prayer, and is it obligatory or recommended, along with clarifying the meaning of the measure "the length of a spear"?

The fatwa referred to does not indicate the obligation to make up the Sunnah of Fajr, but rather the possibility of making it up after the sun has risen. This phrasing does not denote obligation. As for "the height of a spear," it means the sun has risen to the height of a spear in the beholder's eye, which is estimated to be approximately a quarter of an hour.