It’s back. Low-rise jeans, rhinestone belts, butterfly clips — and, unfortunately, the skeletal aesthetic that ruled the early 2000s. On TikTok, the hashtag #Y2KSkinny has racked up millions of views, reviving an ultra-thin ideal many millennials hoped was buried with Myspace. To anyone who remembers the “heroin chic” era or the endless parade of rail-thin…