MOSCOW—Russian opposition leader Alexei Navalny was convicted of fraud and contempt of court and sentenced to nine years in a maximum-security prison on Tuesday, in a trial Kremlin critics see as an attempt to keep President Vladimir Putin’s most ardent foe in prison for as long as possible. A judge also ruled that Navalny would have to pay a fine of 1.2 million rubles (about $11,500). Navalny can appeal the ruling. Navalny, who is already serving 2 and a half years in a penal colony east of Moscow, had been accused of embezzling money that he and his foundation raised over the years and of insulting a judge during a previous trial. The politician has rejected the allegations as politically motivated. The prosecution had asked for 13 years in a maximum-security prison for the anti-corruption crusader and a 1.2 million-ruble fine. It wasn’t immediately clear whether Navalny is expected to …