[.ai] simplify pitfalls #6 and drop the model-storage / injection-test entries
Trim pitfall #6 to the essential point (small dtype diffs compound into a large
final difference), remove the `/tmp` model-storage and incomplete-injection-test
pitfalls, and renumber 1-16 with cross-references updated.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>