Enable caching of YZ-edges #44
Description
_extract_yz_adjacent_pair is called repeatedly, scanning the graph each time to return just one YZ‑edge.
Although this doesn’t alter the algorithm’s overall time complexity, it obscures which YZ‑edges are mergeable at any given moment.
Caching the YZ‑edge set keeps the same cost while making the full list of merge‑ready YZ‑edges instantly available.
Extend the existing implementation to update the cache after each local_complement, pivot, or remove_clifford operation.
Additional context