SpinQuant research harness (fake-quant + Triton INT4 kernels)

Recorded because the SpinQuant W4A4 quality deltas are harness numbers, and 'there is no INT4 tensor-core path for 4x4' is the whole point of the format record. The rotation matrices are ~0.26% of weight size and are folded into the checkpoint. ||| MAINTENANCE (dated fact, GitHub API, 2026-10-04): last commit 2025-02-14 (19.6 months before this record), NO GitHub release or tag found, 2 contributors (distinct committers including anonymous), open_issues_count 31 (issues PLUS pull requests - see [[ev-github-open-issues-count-includes-pull-requests]]), not archived, 432 stars. See [[ev-maintenance-status-is-four-dated-facts]] for how to read this fact set. ||| DEPLOYMENT: NO EVIDENCE OF PRODUCTION DEPLOYMENT FOUND as of 2026-10-04 - repositories, READMEs, docs and issue trackers were searched. See [[ev-production-evidence-is-scarce-and-nearly-always-single-site]] for the grading scheme; note that for an artifact-evaluation or paper-code release, non-deployment is documented intent rather than a negative finding.