Overview of the CXR-LT 2026 Challenge: Multi-Center Long-Tailed and Zero Shot Chest X-Ray Classification. - Hexin Dong; Yi Lin 009; Pengyu Zhou; Xuan Zhong Feng; Alan Clint Legasto; Mingquan Lin; Hao Chen 011; Yuzhe Yang 003; George Shih; Yifan Peng 002 (ISBI, 2026)