The president of Ukraine is facing a confluence of crises testing his ability to lead an increasingly weary nation nearly four years into a devastating full-scale invasion by Russia.For more than a week, Volodymyr Zelenskyy has struggled to contain the fallout from a $100 million corruption scandal implicating top officials and other associates. The pressure on Zelenskyy has ratcheted up as the United States pushes a proposal it drew up with Russia that would require major concessions from Ukraine and seemingly few from Russia to bring an end to the war.All this is playing out as Russia makes slow but...