“Midway through one of her biggest “hits” to date, the hometown-party ode “Townie,” Mitski adds a telling sidenote: “I am not gonna be what my daddy wants me to be.” It wasn’t the first time the Brooklyn singer-songwriter had openly defied expectations in her lyrics, but it was one of her most resonant examples. With “Your Best American Girl,” the lead single from the forthcoming Puberty 2, Mitski ”