WASHINGTON — Election Day is 12 days away. But in courtrooms across the country, efforts to sow doubt over the outcome have already begun.More than 100 lawsuits have been filed this year around the Nov. 8 elections. The legal challenges, largely by Republicans, target rules for mail-in voting, early voting, voter access, voting machines, voting registration, the counting of mismarked absentee ballots and access for partisan poll watchers.The cases likely preview a potentially contentious post-election period and the …