Employee Training Status + Group Tree Aggregation

Requirements Part 1 — get_training_status(employee, training_window, check_day) training_window is the number of days an employee has to complete training, counting from their start_day. check_day is the day we want the status for. Return a status object {name, days_overdue} where name is exactly one of not_required, pending, completed, overdue. Logic derived from the examples: before start_day → not_required; trained on or before check_day → completed (even if the training…