WASHINGTON — The House voted overwhelmingly on Wednesday to shore up federal highway aid and veterans’ health care before heading out of town for its August recess, leaving unresolved an array of sticky issues that are sure to complicate an autumn agenda already groaning under the weight of indecision. In one of their last decisions before adjourning for a month, the House backed a bill that would extend spending authority for transportation programs through Oct. 29, and replenish the federal Highway Trust Fund with $8 billion. That’s enough money to keep highway and transit aid flowing to states through mid-December.