LONDON—World shares rose on Monday, led by sharp gains in energy shares as crude oil prices soared to three-year highs of almost $80 a barrel while European stocks firmed after Germany’s election results ruled out chances of a purely left-wing coalition. Stock markets benefited too from an ostensible easing in Sino–U.S. tensions and Chinese authorities’ decision to pump more cash into financial markets to potentially offset the fallout from embattled real estate firm China Evergrande Group. German shares jumped 1.1 percent, while a pan-European equity index was up half a percent. Gains were led by the energy sector, which rose almost 2 percent while Wall Street too was tipped for a firmer session, with S&P 500 futures up 0.3 percent. Increasing focus is on energy markets where oil futures have climbed around $9 a barrel over September. Brent crude traded on Monday at $79.07 a barrel, while U.S. crude rose …