nx_sort_pairs_candidate_t365.nx

nx_sort.nx -- sorting algorithms. Canonical: this is the substrate-wide canonical sort library per [[feedback-no-tool-proliferation-bit-level]]. Provides: - nx_sort_insertion: O(n^2) cache-friendly bubble-style; substrate canonical for small arrays. - nx_sort_heap: O(n log n) in-place; substrate canonical for larger arrays. - nx_sort_is_sorted: invariant check. Other primitives needing a sort MUST `import "nx_sort.nx"` and compose; re-implementing inline is refused per the cardinal. For quicksort variants see nx_quicksort.nx (separate canonical). - Insertion sort: O(n^2) but cache-friendly, good for small arrays. - Heap sort: O(n log n), in-place, uses sketch_min_heap. Pure i64 ascending order. genealogy_id: williams_1964_heap_sort + insertion_sort_folklore lineage_id: in_place_comparison_sort