[audit] PR #302 merged with empty body: backfill S1-S9 or close

[mattmre]

Audit find (298-PR cross-repo audit, 2026-09-04): PR #302 merged with 0-byte body, 4 commits, 0 headers, 0 reviews. AC: backfill Summary/Scope/AC/Test/Evidence per spec S1-S9 (see BHK#177) or close with reason. Evidence cmd: gh pr view 302 --json body --jq '.body|length' => 0.