Sorted Pair Sum

Implement static int[] pairWithSum(int[] sorted, int target) — return the two INDICES (ascending) of a pair summing to target, or null when none exists. Use two pointers — the sorted order is your invariant. Examples: [1,3,5,8], target 8 → [1,2] (3+5); target 4 → [0,0] is invalid (distinct indices only), so null unless a real pair exists. Duplicate values are allowed as a pair ([3,3], target 6 → [0,1]).

Difficulty: intermediate