Missile strikes hit cities across Ukraine on Tuesday, plunging seven million homes into darkness just days after a humiliating Russian retreat, prompting a defiant response from President Volodymyr Zelensky. Seven million homes were without power following the latest attacks, the presidency said, dampening jubilation over the recapture of Kherson city as world leaders gather at a G20 summit expected to tackle the violence engulfing Ukraine. Lviv in the west and Kharkiv in the east were also attacked on Tuesday, authorities said, with Lviv’s mayor reporting 80 percent of the city was without po…