feat(skills): reviewing-adversarially, one stance for every reviewer

A new skill, voyage:reviewing-adversarially (contract S4): no praise, no
finding without a source (file:line or a quoted line), no downgrade without
a reason, summary-only said and not judged, a Declined to Judge list, claims
checked against the diff rather than the report, axes kept separate.

Red baseline first: six review runs by helpers without the skill (two
invented fixtures) had no separate Declined to Judge list in 6 of 6, an
unsourced finding in 6 of 6, praise in 2 of 6 and a verdict on something
unmeasured in 4 of 6. With the skill: 6 of 6, 0, 0 and 0.

- brief-conformance-reviewer, code-correctness-reviewer, review-coordinator
  and scope-guardian preload it through skills:; the 21-line "Interaction
  Awareness - MANDATORY OVERRIDE" block copied into three of them is gone.
  Each agent keeps its own role.
- The two reviewers and scope-guardian end with their own Declined to Judge
  list; /trekreview names the skill at spawn and passes the reviewers'
  lines to the coordinator, which copies them into review.md as prose
  (the JSON declined_to_judge array and the verdict are unchanged).
- Eval cases 3 / 2 / 1; pins in tests/lib/skills-review-prose-pins.test.mjs.
- tests/fixtures/jsonl-schemas.md: the trekreview-stats line_ref moves with
  Phase 8 (636-686).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

commands/trekreview.md

@@ -381,6 +381,15 @@ message, multiple tool calls.
 
 Reviewers run independently. Do NOT pre-feed findings between them.
 
+**Reviewer stance: the `reviewing-adversarially` skill.** Both reviewers and
+the coordinator have `voyage:reviewing-adversarially` preloaded through their
+`skills:` line. Name it in every reviewer prompt anyway, so the rules hold even
+where preloading did not happen: "Follow the reviewing-adversarially skill: no
+praise; every finding cites file:line or quotes the line; no downgrade without
+a reason; say what you read in full and what only as a summary; list what you
+did not judge under ### Declined to Judge; check claims against the diff, not
+a report."
+
 | Agent | Mode-gated | Purpose |
 |-------|------------|---------|
 | `brief-conformance-reviewer` | Skipped in `quick` | Trace each Success Criterion + Non-Goal to delivered code. Emits findings tagged with rule_keys from the conformance/scope categories. |
@@ -478,7 +487,11 @@ forbids `ALLOW` (`lib/review/coordinator-contract.mjs`, `missing_reviewers`).
 Launch `review-coordinator` (Agent tool) with the merged findings array
 from Phase 5 AND the Phase 4.7 engine payloads, plus the triage map, brief
 metadata, SHA range, the expected reviewer set (engines included), and each
-not-run engine with its reason.
+not-run engine with its reason. Name `voyage:reviewing-adversarially` in the
+coordinator's prompt as in Phase 5, and pass each reviewer's
+`### Declined to Judge` lines verbatim from its saved
+`{project_dir}/.review-out-{reviewer}.md`: the coordinator copies them into
+`## Declined to Judge`, so nothing a reviewer set aside disappears.
 
 **Brief choices.** Next to the brief metadata, pass the brief's choices
 verbatim: extract the `## Non-Goals`, `## Constraints` and `## Preferences`