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/i18next-fs-backend/index.d.ts

@@ -0,0 +1,50 @@
+import { BackendModule, ReadCallback } from "i18next";
+
+type LoadPathOption =
+  | string
+  | ((language: string, namespace: string) => string);
+
+type AddPathOption =
+  | string
+  | ((language: string, namespace: string) => string)
+
+export interface FsBackendOptions {
+  /**
+   * path where resources get loaded from, or a function
+   * returning a path:
+   * function(language, namespace) { return customPath; }
+   * the returned path will interpolate lng, ns if provided like giving a static path
+   */
+  loadPath?: LoadPathOption;
+  /**
+   * path to post missing resources, must be `string` or a `function` returning a path:
+   * function(language, namespace) { return customPath; }
+   */
+  addPath?: AddPathOption;
+  ident?: number | undefined;
+  parse?(
+    data: string
+  ): { [key: string]: any };
+  stringify?(
+    data: { [key: string]: any }
+  ): string;
+  expirationTime?: number;
+}
+
+export default class I18NexFsBackend
+  implements BackendModule<FsBackendOptions>
+{
+  static type: "backend";
+  constructor(services?: any, options?: FsBackendOptions);
+  init(services?: any, options?: FsBackendOptions): void;
+  read(language: string, namespace: string, callback: ReadCallback): void;
+  create?(
+    languages: string[],
+    namespace: string,
+    key: string,
+    fallbackValue: string
+  ): void;
+  type: "backend";
+  services: any;
+  options: FsBackendOptions;
+}