Toward AI-Assisted Precision Diagnostics in Breast Cancer: Source-Group-Preserving Evaluation of Class-Imbalance Strategies for Ordered ER-IHC Segmentation - Md Saiful Arefin; Mohammad Saiful Islam; Md Serajun Nabi; Rashadul Islam Sumon; Maria Lapina; Vitalii Lapin; Mohammed Muthanna (Diagnostics, 2026)