fix: close the six defects an independent review found in the trial fixes

Independent read-only review of c56f852..2d29966 (2026-10-08), each defect
reproduced by the reviewer; each new test fails on that code.

- test-lock green ran ANY allowlisted command: `green --cmd "git status"`
  marked a red step green and the stop guard let it stop. The lock now
  stores the step's test command (`lock --cmd`); `green` runs only that
  one (a different --cmd, or a lock without one, exits 2). trekexecute D1
  calls `green` with no command, which also removes the quoting hazard.
- plan-gate --accept-open worked at round 1 and passed the gate; it now
  refuses while rounds are left.
- findings-schema --repo-root swallowed a following flag, or took a root
  that does not exist, and silently skipped the line check: exit 2.
- brief-review-stamp hashed only the body, so a changed `framing` or
  `research_topics` stayed "current"; it now covers the reviewed
  frontmatter too (only the post-review stamps are left out).
- red-proof red_kind read an assertion message naming SyntaxError as a
  load error; the signatures are now specific.

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

lib/validators/plan-gate.mjs

@@ -25,8 +25,8 @@
 //     After the operator's explicit yes to "build as is": records the open
 //     MAJORs of the current round as accepted (`accepted_open` in the verdict
 //     block, bound to the round and the plan hash). 0 = written; 1 = refused
-//     (a BLOCKER is open, no MAJOR is open, or the verdict is stale); 2 = could
-//     not run.
+//     (rounds left, a BLOCKER is open, no MAJOR is open, or the verdict is
+//     stale); 2 = could not run.
 //
 // Open MAJORs (operator decision 2026-10-08, voyage-lekerepo trial point 6):
 // they used to pass as warnings, and after the last round there was no way to
@@ -271,6 +271,10 @@ export function acceptOpen(rawText, opts = {}) {
   if (v.findings.some(f => sevOf(f) !== 'major' && sevOf(f) !== 'minor')) return { code: 1, message: 'a BLOCKER is open; a blocker is never accepted' };
   const majors = v.findings.filter(f => sevOf(f) === 'major');
   if (majors.length === 0) return { code: 1, message: 'no MAJOR is open; nothing to accept' };
+  // Only the last round: with rounds left the answer is to revise, not accept
+  // (found by the independent review: acceptance at round 1 passed the gate).
+  const left = v.max_rounds + (v.extra_rounds ?? 0) - v.round;
+  if (left > 0) return { code: 1, message: `${left} critic round(s) left: revise the plan and run the next round; acceptance is only for after the last round` };
   const accepted = {
     ...v,
     accepted_open: {