Student Performance Dashboard with Dynamic Enrollment Segmentation

Design a PostgreSQL stored procedure that generates a comprehensive student performance dashboard, automatically segmenting enrollment data across multiple academic years. The procedure must calculate grade point averages, retention rates, and performance trends using window functions. Include logic to dynamically filter data by department, program, and cohort year, with output compatible with Google Sheets for visualization. Ensure the procedure handles null values gracefully and provides percentile ranking for student achievement.