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/cross-fetch/index.d.ts

@@ -0,0 +1,14 @@
+/// <reference lib="dom" />
+
+declare const _fetch: typeof fetch;
+declare const _Request: typeof Request;
+declare const _Response: typeof Response;
+declare const _Headers: typeof Headers;
+
+declare module "cross-fetch" {
+  export const fetch: typeof _fetch;
+  export const Request: typeof _Request;
+  export const Response: typeof _Response;
+  export const Headers: typeof _Headers;
+  export default fetch;
+}