The Clintons’ role in the Democratic Party has been a source of debate since the election last fall. On Friday, in a video for DNC members, the former nominee tied her campaign and 2016 party platform to the so-called resistance movement. ATLANTA — Wading back into politics for one of the first times since the end of her campaign, Hillary Clinton promised Democrats meeting here in Atlanta that she will stay active in the party’s efforts to rebuild and to oppose President Donald Trump. “We as Democrats must move forward with courage, confidence, and optimism, and stay focused on the...