Restructure the 6-tab settings layout: a left vertical tab rail on desktop (lg) with content beside it, and a horizontally scrollable row on mobile with labels always visible (were icon-only, ambiguous). Tab triggers are now mapped from a single TAB_ITEMS array instead of being hand-repeated. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>