Zepto has more than doubled its valuation to $3.6 billion from $1.4 billion in less than a year in a new funding round of $665 million as the Mumbai-based startup intensifies the quick commerce competition in the world’s second largest internet market. Zepto sells and delivers everything from grocery items to electronic gadgets within 10 minutes to consumers in urban Indian cities. The rapid-delivery model is thriving in India even as most startups in the space have cratered in developed markets...