LONDON — In hindsight, the dream of a “brat summer” 2024 was always a mirage. On the surface, there was so much potential. The sun was shining, the rosé was on ice, and an achingly cool new album by British pop star Charli XCX — “BRAT” — was lined up as the soundtrack. The memes were good, the songs catchy, the TikTok dances groovy. But then … something happened. Kamala Harris was announced de-facto Democrat candidate for U.S. president, and Charli XCX declared that Kamala was brat. Politicos who should know better went wild. They too wanted to be brat —…