HONG KONG—Han Dongfang, a veteran Tiananmen Square activist, says Hong Kong should not lose heart despite a heavy China-led crackdown on its freedoms, as he defied police warnings and sat quietly on a park bench to commemorate the victims of June 4. Han, who was almost killed when Chinese soldiers opened fire on pro-democracy protesters in Beijing in 1989, and was then jailed and forced into exile, was one of the few people in Hong Kong’s Victoria Park on Friday afternoon, ignoring a police ban on an annual candlelight vigil, ostensibly imposed as part of coronavirus restrictions. Clad in a black T-shirt and yellow mask to ward off the virus, and seated next to an old banyan tree, Han spoke of the importance of keeping truths alive, and of not succumbing to fear. “Today, I just feel like being here,” the 58-year-old, with a long salt and pepper beard, and …