Online accounts say there's a radiation source for heating during the lunar night, but it seems one of the solar panels used for normal operations didn't fold up properly (by folding up these panels are closer to the heat source) before the sun went down, and that exposed component froze and was ruined, which sealed the spacecraft's fate.

Source: http://www.dvice.com/2014-2-12/chinas-jade-rabbit-lunar-rove...

Looks like it: http://en.wikipedia.org/wiki/Timeline_of_the_Republic_of_Chi...

They had capability to produce required material decades ago.

They also have sufficient nuclear arsenal to warrant maintaining stockpiles of the stuff: http://en.wikipedia.org/wiki/China_and_weapons_of_mass_destr...

You are confusing the Republic of China, commonly called Taiwan (which is the subject of your first link) with the People's Republic of China, which sent this robot to the moon.

Both of them have nuclear power though (but only PRC has nuclear weapons) and radioactive material in sufficient quantities.

It has a radioisotope heating unit https://en.wikipedia.org/wiki/Yutu_%28rover%29#Specification...