Upgrade UI i18n wrapper to i18next

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/package.json

@@ -20,6 +20,7 @@
     "build-storybook": "storybook build -c storybook/.storybook -o storybook-static",
     "preview": "vite preview",
     "typecheck": "tsc -b",
+    "test": "vitest run",
     "clean": "rm -rf dist storybook-static tsconfig.tsbuildinfo",
     "prepack": "rm -f package.dev.json && cp package.json package.dev.json && node ../scripts/generate-ui-package-json.mjs",
     "postpack": "if [ -f package.dev.json ]; then mv package.dev.json package.json; fi"