Assemble: Leaderboard Queries

A game keeps one score per player in an array. Implement the four queries a leaderboard needs, using sorting and partial sorting rather than Python loops. top_k returns the indices of the k highest scores (highest first, ties by lower index), competition_ranks gives every player a 1-based rank where equal scores share the best rank ("1, 2, 2, 4"), kth_largest returns the k-th largest value without sorting the whole array, and percentile_rank reports what fraction of the scores each player strictly beats.