The financial crisis that has made Detroit one of the largest cities ever to face mandatory state oversight was decades in the making, a trail of missteps, of trimming too little, too late, of hoping that deep-rooted structural problems would turn out to be cyclical downturns that might melt away as the economy picked up. Some factors were out of the city’s control. As auto industry jobs moved elsewhere over the decades, for example, Detroit lost much of its affluent tax base.