5-epoch DFA training on CIFAR-10 + apply protocol + interpret verdict.
Self-contained, runs on CPU in <2 minutes. Demonstrates the API a future
paper author would use:

  1. train your model (any FA-style method)
  2. build eval_batches from your test loader
  3. call diagnose(model, eval_batches, headline_acc, frozen_baseline_acc)
  4. read report.verdict; walk back if 'needs walk-back'

Not run during this session to avoid GPU contention with the in-flight
direction-quality and ViT/ResNet experiments.