test: delete tests of dead eval code (A)

- A1: the retired Eng lexical oracle (evaluateEngSeedCoverage,
  isEngSeedDecisionAUQ), the completion-handoff detector and the retained
  corpus had no paid caller since v1.87.6; delete their 26 replay files,
  ~2.6k helper LOC and fixtures, and the dead blocks in 8 mixed files
  (live hasNativePlanTerminal / batching assertions stay).
- A2: dead viewport approvers in autoplan-artifact-permission and their 11
  replay files + fixtures; recorder/launcher cases stay.
- A3: never-wired oracles and seeders (autoplan-phase-order,
  eng-finding-fixture, ceo-paired-fixture, design-ui-scope,
  plan-skill-completion, pty-current-screen, required-reads,
  transcript-section-logger); plan-seed-submission now decodes through the
  production createPtyScreen; section manifests name their actual guard.
- A4: zero-reference helper exports, plus execGit and invokeAndObserve
  found by the reachability pass.
- 52 fixtures orphaned by the deletions; touchfile and selection-table
  entries for every deleted path.

test/helpers/scratch-repo.ts

@@ -33,18 +33,6 @@ export function gitArgvIn(repoDir: string, args: string[], timeout = 5000) {
   return spawnSync('git', [...GIT_HERMETIC_ARGS, ...args], { cwd: repoDir, timeout });
 }
 
-/** Create a scratch repo (mkdtemp) with an initial commit; caller cleans up. */
-export function makeScratchRepo(prefix: string, files: Record<string, string> = { 'src.txt': 'v1\n' }): string {
-  const repoDir = fs.mkdtempSync(path.join(os.tmpdir(), prefix));
-  gitIn(repoDir, 'init -q -b main');
-  for (const [name, content] of Object.entries(files)) {
-    fs.writeFileSync(path.join(repoDir, name), content);
-  }
-  gitIn(repoDir, `add ${Object.keys(files).join(' ')}`);
-  gitIn(repoDir, 'commit -q -m init');
-  return repoDir;
-}
-
 /** Recursively find files with a given suffix under a directory. */
 export function findFilesBySuffix(root: string, suffix: string): string[] {
   const found: string[] = [];