Eileen Gu of China has become the first Olympic champion in the women’s freestyle big air, taking gold at the Beijing Winter Games on Tuesday. The 18-year-old earned the highest score of 94.5 on her third run at the new Big Air Shougang venue. Her two best scores put her top of the standings on 188.25. Gu said the win was the best moment of her life. “The happiest moment, day, whatever — of my life. I just cannot believe what just happened.” She decided to pull out a “random trick”, a left double cork 1620, for her final run, knowing she was guaranteed a podium spot. “Even if I didn’t land it,…