Add internationalization support with astro-i18next integration

- Implemented astro-i18next for multi-language support, including English, Dutch, and Italian.
- Configured default locale and language fallback settings.
- Defined routes for localized content in the configuration.
- Updated package.json and package-lock.json to include new dependencies for i18next and related plugins.

node_modules/iso-639-1/.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+  "eslint.enable": true,
+  "eslint.packageManager": "yarn",
+  "prettier.eslintIntegration": true
+}