As China's Gen Z rejects the corporate grind, craft beer has become an unlikely symbol of economic change and cultural reinvention.For years, I thought I understood China very well. I was born and raised there, fluent in both Mandarin and Cantonese. Even after years away I followed the politics and social trends as part of my job as a journalist. I was certain I knew my country of birth — at least my Gen Z peers.Then, on a midsummer night last year, I took a sip of lager at a craft beer pub in my hometown in China's southern province…