TAIPEI, Taiwan — Since Russia invaded Ukraine, Justin Huang, a 23-year-old recent university graduate in Taiwan, has been gripped by news of the crisis, just like many other people around the world. He has pored over reports about Ukrainians signing up for the military and scrutinized video footage of Russian missiles hitting residential buildings. He has been deeply disturbed by Russia’s brazen disregard for global norms. But for Mr. Huang and many Taiwanese, Russia’s assault is hitting especially close to home. The self-governed island democracy has long faced the threat…