By Cynthia Kim, Yena Park and Jihoon Lee SEOUL (Reuters) -South Korea's trade talks with the Trump administration have become increasingly dogged by political doubts this week, spooking investors who now worry Seoul may end up with a raw deal or perhaps no deal at all. The Korean won broke through the psychologically important 1,400 to the dollar level on Thursday, seen by markets as authorities' line in the sand against bearish speculative bets and opening the way for further downside. The selling ga ...