feat: Migrate frontend from static HTML to Next.js 16 App Router

feat: Migrate frontend from static HTML to Next.js 16 App Router

fix: no transition on reload + AI search fix + skeletons everywhere + hide search btn

feat: slower transition + seller settings & academy pages

fix: iOS nav stack — complete swipe-back + skeleton loader + nav fix

fix: restore fast search (Promise.all parallel) + playable skeleton loader (draggable C + cards)

feat: premium UX — spotlight search (glassmorphic+stagger), physics loader (draggable C), spring swipe-back, magnetic buttons, optimistic UI bursts, framer-motion page transitions

feat: pure white design (no cyan) + AI-powered search + animations + page transitions + skeleton loaders