Interactive scaling-laws (TPP) explainer

Details

Adds the 'Interactive · scaling laws' section: a loss-encoding, animated, in-browser scaling-law explainer (faithful port of the paper's fitter, pinned against Python goldens) + the tpp-examples data suite. Also completes the ⌘K jump-to TOC and the priority-overflow top nav.

Files changed

Integration (merge) commit — no direct file changes.