chore(#469): clear residual warn-level lint in effort test files (#470)

Remove unused `os` import left by #463's effort-API conversion and fix
two no-useless-escape chars in codex-config test description string.
Part of ESLint harness cleanup effort (#452).

Co-authored-by: CI Rebase Check <ci@gsd-redux>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/codex-config.test.cjs

@@ -2223,7 +2223,7 @@ describe('Codex uninstall symmetry for hook-enabled configs', () => {
     assert.strictEqual(countMatches(cleaned, /\[agents\.gsd-/g), 0, 'removes managed GSD agent sections');
   });
 
-  test('install then uninstall preserves a pre-existing quoted [features].\"codex_hooks\" = true', () => {
+  test('install then uninstall preserves a pre-existing quoted [features]."codex_hooks" = true', () => {
     writeCodexConfig(codexHome, [
       '[features]',
       '"codex_hooks" = true',

tests/feat-3023-model-phase-types.test.cjs

@@ -24,7 +24,6 @@ const { test, describe, beforeEach, afterEach } = require('node:test');
 const assert = require('node:assert/strict');
 const fs = require('node:fs');
 const path = require('node:path');
-const os = require('node:os');
 
 const {
   resolveModelInternal,