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/@proload/plugin-tsm/lib/index.d.ts

@@ -0,0 +1,5 @@
+import { Plugin } from '@proload/core';
+
+declare const typescriptPlugin: Plugin;
+
+export default typescriptPlugin;