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/src/main.tsx

@@ -2,6 +2,7 @@ import React from "react";
 import ReactDOM from "react-dom/client";
 import App from "./App.tsx";
 import "./index.css";
+import "./i18n/config";
 
 ReactDOM.createRoot(document.getElementById("root")!).render(
   <React.StrictMode>