review-plan: a malformed review-log row keeps the first-pass Red Team (GSTA-167 fail closed)

A readable log whose rows do not parse counted as no record, so it took
the first-pass cut. It now keeps the Red Team like an unreadable log;
a missing or empty log still takes the cut. lib/review-depth.ts and
DEPTH_RULES (e9281c6c3758ea0f) unchanged, so no repin.

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

docs/review-policy.md

@@ -229,7 +229,7 @@ review log is the `<branch>-reviews.jsonl` file that `gstack-review-log` writes
 `review-fix-check`, `adversarial-review`, `codex-review`, `design-review-lite` or
 `ship` skills. So a new `/ship` after a stop, on a branch an earlier run already
 reviewed, runs the Red Team on its first full pass, as it did before this rule.
-When the log can't be read, the plan keeps the Red Team too. `gstack-review-plan
+When the log can't be read, or holds a line that isn't valid JSON, the plan keeps the Red Team too. `gstack-review-plan
 --json` reports the lookup as `reviewed_before`: true, false, or null when the log
 was unreadable. `RED_TEAM_FIRST_PASS` (false) records the rule in
 `DEPTH_RULES`.