Dual-ratio covers + heading pages for reading stories

walkingweekend.com /reading surfaces render only the 1200x675 cover (pages[0].image_file) and ignore image_file_vertical, which the pipeline now generates for the cover and every page. Scope: components/redraw-toc.tsx story cover grid (L119-147, 218-238) + story/magazine page thumbs (L437-648); components/redraw-main.tsx resource pane (L218-229); components/json-editor.tsx cover preview (L217-218); lib/reading-cdn.ts CDN config cover fallback (L164-168 — also emit cover_vertical). Generation side (lovart redraw + textToPages heading) is already vertical-aware; benben.im + hygge.im readers already art-direct. Book/magazine config covers, selling surfaces, og:image: out of scope. components/reader/Pages.tsx + Gallery.jsx are orphaned dead code — candidates for deletion in the same pass.