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/question-preference-hook.test.ts

@@ -730,6 +730,7 @@ describe('Conductor spawned deny (#2733)', () => {
       const scriptKind = spawnSync(BIN, [], {
         env: { PATH: process.env.PATH ?? '/usr/bin:/bin', ...env },
         encoding: 'utf-8',
+        timeout: 30_000,
       }).stdout.trim();
       expect(
         spawnedByEnv(env),