SCMP reporter Holly Chik speaks with video journalist Thomas Yau from the Puxi district on bartering for food, increasingly violent street clashes appearing on social media and protest banners demanding Covid deaths be acknowledged. Shanghai-based NYU economics professor Rodrigo Zeidan analyses the growing buildup of cargo ships outside Shanghai's port and what it means for global trade. Senior correspondent William Zheng looks at Xi Jinping's political challenges with Shanghai in the leadup to…