fix: round 6 of the release review of 6.3.0

Round 6 (v6.2.0..c3641ff, WARN: 11 MAJOR, 3 MINOR; 0 BLOCKER). The round-5
fixes hold (code-correctness-reviewer); three of the new MAJOR were side
effects of running checks with no shell. Each fixed behind a test that
failed first on c3641ff.

- git checks stay in the repo too: no path that climbs out with .., starts
  at / or reads <rev>:../x, and no --no-index (both reviewers).
- A trailing `# comment` on a shell-fence line is dropped: with no shell,
  its words made an honest check NOT RUN, among them the first check of the
  shipped example plan.
- A glob reaches `node --test` only on Node 21 and later, which expands it
  itself; on an older Node it is refused with that reason (engines >=18).
- With no shell, exit 126/127 is the test program's own: red proof reads it
  as a red (the control run still tells an environment fault apart), the
  done line and the test lock as a failure.
- A runner that could not start (not installed) is NOT RUN in the criteria
  runner and not-run (exit 2) in regression-check, as red-proof and
  done-line already said; never a red suite.
- Tests-only: a backticked `Makefile` alone in its entry is a path, and red
  proof confirms the plan's tests-only reading against the step's own diff
  (the altitude finding: the diff is a fact, the Files: prose is not).
- release-check stops a suite that never ends (15 minutes) and reads it as
  not measured (exit 2).
- The two lines this release added to pre-bash-executor.mjs are ASCII.
- MINOR: git and the other runners share one plain-word pattern.

Not in this round: MINOR f00a2eb8 (shared norm/ticked-path and isMain
helpers) and MINOR on plan-review-dedup's repeated tokenizing.

Suite 2194 (2192/0/2).

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

docs/HANDOVER-CONTRACTS.md

@@ -269,7 +269,7 @@ prose form (relaxed in S26 so the template's prose emission parses).
 7. **Every plan_version, no version bump** (a plan without the field validates unchanged; voyage-lekerepo trial 2, 2026-10-08):
    - **K10 — `Regression:`** (optional step field): ONE backticked command the criteria runner's allowlist runs, with no pipe and no `&&` (first backticked span, as for `Verify:`). The executor runs it green before the step's checkpoint; a step without it runs nothing new. `Verify:` stays the step's own red-first test. One that can never run is `PLAN_STEP_REGRESSION_NOT_RUNNABLE` (an error; a warning under `--soft`).
    - **K11 — `On failure:`** opens with one of `revert`, `retry`, `skip`, `escalate` (case-insensitive; a leading `**`, `_`, backtick or `-` is ignored, other leading characters are not; `onFailureAction` in `lib/parsers/plan-schema.mjs`), the words `/trekexecute` reads; any other opening is the warning `PLAN_STEP_ON_FAILURE_UNKNOWN`. A missing `On failure:` is unchanged (the executor defaults to `escalate`).
-   - **A step of only tests** (order 10, voyage-lekerepo trial 3, 2026-10-09): when every file in a step's `Files:` is a test (its `Test first:` file, or a path `lib/util/test-path.mjs` reads as a test: under `tests/`, `test/`, `__tests__/`, `spec/`, `specs/`, or named `*.test.*`, `*.spec.*`, `*_test.*`, `*_spec.*`, `test_*.py`, but never a document such as `docs/specs/api.md`; `stepTestsOnly` in `lib/parsers/plan-schema.mjs`), the warning is `PLAN_STEP_TESTS_ONLY`: the behaviour its tests cover exists at its start point, so it can never be proven red. A step without `Files:` is not judged. At run time `red-proof.mjs --plan <plan.md> --step <N>` puts the same reading on a `not-red-at-base` as `tests_only`, and `/trekexecute` sends a `tests_only: true` step straight up to the plan.
+   - **A step of only tests** (order 10, voyage-lekerepo trial 3, 2026-10-09): when every file in a step's `Files:` is a test (its `Test first:` file, or a path `lib/util/test-path.mjs` reads as a test: under `tests/`, `test/`, `__tests__/`, `spec/`, `specs/`, or named `*.test.*`, `*.spec.*`, `*_test.*`, `*_spec.*`, `test_*.py`, but never a document such as `docs/specs/api.md`; `stepTestsOnly` in `lib/parsers/plan-schema.mjs`), the warning is `PLAN_STEP_TESTS_ONLY`: the behaviour its tests cover exists at its start point, so it can never be proven red. A step without `Files:` is not judged. At run time `red-proof.mjs --plan <plan.md> --step <N>` puts the same reading on a `not-red-at-base` as `tests_only`, true only when every file the step changed since its start point is a test too, and `/trekexecute` sends a `tests_only: true` step straight up to the plan.
 
 **Validation strategy:**