test: review-army + adversarial test hardening

- Tripwire scans execFileSync too (ceiling 8: two more grep-needle string
  exemptions); merge-introduced timeout-less spawnSync in
  question-preference-hook fixed — the tripwire caught a site that landed
  on main AFTER the sweep, on its first day.
- gstack-detach gains TWO watchdog kill regression tests: TERM-immune
  grandchild (the killpg-after-grace escalation) and the leader-dies
  variant (the pgid-at-spawn fix — the case the first test cannot see).
- eval-flake-rank gets its unit suite (final-attempt accounting, artifact
  exclusion, shard recursion, recency bound).
- Groupkill/startup-grace shim markers are per-run unique (pid-suffixed
  sleep durations): sibling Conductor worktrees run free suites with no
  machine lock, and fixed markers let one run pgrep/pkill the other's
  shims — a cross-run flake inside the anti-flake tests.
- flake-ledger test pins the project-scoped local default; stale empty
  section headers in touchfiles-data deleted (they invited entries under
  deliberately retired categories).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

test/spawnsync-timeout-tripwire.test.ts

@@ -37,7 +37,7 @@ const SCAN_ROOTS = [
   'browser-skills',
 ];
 
-const SYNC_SPAWN = /\b(?:spawnSync|execSync|Bun\.spawnSync)\s*\(/;
+const SYNC_SPAWN = /\b(?:spawnSync|execSync|execFileSync|Bun\.spawnSync)\s*\(/;
 /** Generous on purpose: multi-line arg arrays push the options object far
  *  below the call line (observed: +13 lines in codex-model-probe). A wide
  *  window trades a sliver of false-negative risk for zero rename churn. */
@@ -48,7 +48,7 @@ const EXEMPT_MARKER = /tripwire-exempt:/;
 const COMMENT_LINE = /^\s*(?:\/\/|\*|\/\*)/;
 
 /** Shrink-only: lower it when exemptions burn down; never raise it. */
-const EXEMPT_CEILING = 6;
+const EXEMPT_CEILING = 8;
 
 const SELF = path.join('test', 'spawnsync-timeout-tripwire.test.ts');