Imagine stepping into a massive factory where robots churn out smartphones nonstop, lights off, without any human intervention in sight. China's dark factories are setting a new benchmark in the manufacturing world, pushing boundaries with round-the-clock automation that feels straight out of sci-fi.They have set-up dark factories, where "lights-out" operations mean a huge change, with less dependency on people and more on machines that never tire.While these factories seem to be out of an animated movie, they are actually real in China, where machines operate together without human intervention to produce output in bulk.But what are these factories and why…