fix(#3190): commit review.md in --auto loop; fix report env var (#3434)

* fix(#3190): commit review.md in --auto loop; fix report env var

Three coupled defects in gsd-core/workflows/code-review-fix.md:

- The --auto re-review loop overwrote REVIEW.md each iteration but the
  single docs commit staged only REVIEW-FIX.md, so the committed REVIEW.md
  stayed at iteration 1 and contradicted the committed REVIEW-FIX.md. The
  --auto commit now stages the converged REVIEW.md alongside REVIEW-FIX.md
  (guarded on AUTO_MODE; non-auto single-pass runs unchanged).
- The two inline frontmatter validators (HAS_STATUS, FIX_FRONTMATTER)
  exported REVIEW_PATH into a node -e body that reads process.env.
  FIX_REPORT_PATH, so the status check was always empty and REVIEW-FIX.md
  was never committed. Both now export FIX_REPORT_PATH.
- On successful convergence the spent .iterN.md backups are removed so the
  phase directory is clean; they are retained on degradation for post-mortem.

Regression test: tests/code-review-fix-pipeline-regression.test.cjs.

* chore(#3190): set changeset pr to 3434

---------

Co-authored-by: sim <sim@local>

scripts/lint-allow-test-rule-refs.ceiling.json

@@ -1,4 +1,4 @@
 {
-  "maxFiles": 299,
+  "maxFiles": 300,
   "grace": 3
 }