feat: Add Russian i18n translations and fix CORS + API endpoint issues

- Implemented full Russian translation (ru) for 8 major pages
- Added LanguageSwitcher component with language detection
- Translated: Navigation, Settings, Workflows, Credentials, Banner, Examples
- Fixed API endpoint path: changed to use sans-api-v1 client for /v1/ endpoints
- Fixed CORS: added http://localhost:8081 to ALLOWED_ORIGINS
- Added locales infrastructure with i18next and react-i18next
- Created bilingual JSON files (en/ru) for 4 namespaces
- 220+ translation keys implemented
- Backend CORS configuration updated in .env
- Documentation: I18N implementation guides and installation docs

skyvern-frontend/package.json

@@ -24,6 +24,7 @@
     "@codemirror/lang-python": "^6.1.6",
     "@dagrejs/dagre": "^1.1.4",
     "@hookform/resolvers": "^3.3.4",
+    "@microsoft/fetch-event-source": "^2.0.1",
     "@novnc/novnc": "1.5.x",
     "@radix-ui/react-accordion": "^1.1.2",
     "@radix-ui/react-aspect-ratio": "^1.0.3",
@@ -56,9 +57,11 @@
     "country-state-city": "^3.2.1",
     "cross-spawn": "^7.0.6",
     "embla-carousel-react": "^8.0.0",
-    "@microsoft/fetch-event-source": "^2.0.1",
     "express": "^4.21.2",
     "fetch-to-curl": "^0.6.0",
+    "i18next": "^25.8.13",
+    "i18next-browser-languagedetector": "^8.2.1",
+    "i18next-http-backend": "^3.0.2",
     "nanoid": "^5.0.7",
     "open": "^10.1.0",
     "posthog-js": "^1.138.0",
@@ -68,6 +71,7 @@
     "react-draggable": "^4.5.0",
     "react-github-btn": "^1.4.0",
     "react-hook-form": "^7.51.1",
+    "react-i18next": "^16.5.4",
     "react-router-dom": "^6.30.2",
     "serve-handler": "^6.1.6",
     "tailwind-merge": "^2.2.2",