Codifies the 'iconic lab book' framing (SICP / K&R / Three Easy Pieces
/ H&P slot), voice register, project conventions (no mid-doc HRs, no
emoji in PDF body prose, conditional-content pattern for HTML cards,
{python} shortcode trap), the change-budget per chapter, and the
return-report format. Single source of truth for the parallel
chapter-by-chapter narrative-quality pass.
Filename avoids the existing **/*_REVIEW*.md gitignore pattern in
tinytorch/.gitignore (which excludes review-notes scratch files).
