(Reuters) – President Volodymyr Zelenskiy sidelined his childhood friend as head of Ukraine’s security service, and another close ally as top prosecutor, in the biggest internal purge of the war, citing their failure to root out Russian spies. FIGHTING * A Russian shell smashed into a two-storey building in the eastern Ukrainian town of Toretsk on Monday, killing six civilians who were sheltering there, the State Emergency Service said. * Russian Defence Minister Sergei Shoigu ordered generals to prioritise destroying Ukraine’s long-range missile and artillery weapons after Western-supplied we…