The Federal Trade Commission last week proposed a blockbuster rule that, if adopted, would ban all noncompetition agreements in employment contracts, working one of the most fundamental shifts in employer-employee relationships in decades.The rule would supersede all inconsistent state laws. The proposal would continue to allow, however, noncompete agreements entered into as part of the sale of a business.The FTC adopted the rule by a 3-1 vote, saying that banning noncompetes in employment agreements could raise workers …