feat(i18n): Complete localization of marketing frontend with react-i18next, prefixed URLs, JSON migrations, and automation

docs/prp/07-guest-pwa-routes-components.md

@@ -81,7 +81,8 @@ apps/guest-pwa/
       usePollStats.ts           // polls /events/:slug/stats every 10s
       usePollGalleryDelta.ts    // polls /events/:slug/photos?since=...
     i18n/
-      de.json
+      config.ts  // i18next init with react-i18next, backend loadPath '/lang/{{lng}}/guest.json'
+      de.json    // Namespace: guest (e.g., { "gallery": { "title": "Galerie" } })
       en.json
     main.tsx
     App.tsx
@@ -145,6 +146,7 @@ State & Data
 - TanStack Query for server data (events, photos); optimistic updates for likes.
 - Zustand store for local-only state (profile, queue, banners).
 - IndexedDB for upload queue; CacheStorage for shell/assets.
+- i18n: react-i18next; load 'guest' namespace JSON from /lang/{locale}/guest.json; path-based detection for /de/e/:slug, /en/e/:slug; useTranslation('guest') in components.
  - Polling: focus-aware intervals (10s stats, 30s gallery); use document visibility to pause; backoff on failures.
 
 Accessibility & Performance