Find all pairs summing to target in sorted array

Given a non-decreasing array of integers nums and an integer target, return all unique pairs of indices (i, j) with i < j such that nums[i] + nums[j] == target. Use 0-based indices and list pairs in increasing order of i, then j. Each value may be used at most once per pair; if duplicates create the same value pair, include that pair only once. Aim for an O(n) two-pointer solution and analyze complexity.