Write a function slice_scores(scores, k) that receives a list of player scores and a non‑negative integer k. Return a tuple (first_k, last_k_reversed, middle) where:
- first_k – the first k elements (or the whole list if k exceeds its length).
- last_k_reversed – the last k elements in reverse order (empty if k is 0).
- middle – the list after removing the first k and the last k elements (may be empty).
Examples:
slice_scores([10,20,30,40,50], 2) # → ([10,20], [50,40], [30])
slice_scores([1,2,3], 0) # → ([], [], [1,2,3])