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/test/test.js

@@ -0,0 +1,92 @@
+const assert = require('assert');
+const ISO6391 = require('../build/index');
+
+describe('getName()', function() {
+  it('en', function() {
+    assert.equal(ISO6391.getName('en'), 'English');
+  });
+  it('zh', function() {
+    assert.equal(ISO6391.getName('zh'), 'Chinese');
+  });
+  it('xx', function() {
+    assert.equal(ISO6391.getName('xx'), '');
+  });
+  it('toString', function() {
+    assert.equal(ISO6391.getName('toString'), '');
+  });
+});
+
+describe('getNativeName()', function() {
+  it('en', function() {
+    assert.equal(ISO6391.getNativeName('en'), 'English');
+  });
+  it('zh', function() {
+    assert.equal(ISO6391.getNativeName('zh'), '中文');
+  });
+  it('xx', function() {
+    assert.equal(ISO6391.getNativeName('xx'), '');
+  });
+  it('toString', function() {
+    assert.equal(ISO6391.getNativeName('toString'), '');
+  });
+});
+
+describe('getCode()', function() {
+  it('English', function() {
+    assert.equal(ISO6391.getCode('English'), 'en');
+  });
+  it('Chinese', function() {
+    assert.equal(ISO6391.getCode('Chinese'), 'zh');
+  });
+  it('中文', function() {
+    assert.equal(ISO6391.getCode('中文'), 'zh');
+  });
+  it('xx', function() {
+    assert.equal(ISO6391.getCode('xx'), '');
+  });
+  it('toString', function() {
+    assert.equal(ISO6391.getCode('toString'), '');
+  });
+});
+
+describe('validate()', function() {
+  it('en', function() {
+    assert.equal(ISO6391.validate('en'), true);
+  });
+  it('zh', function() {
+    assert.equal(ISO6391.validate('zh'), true);
+  });
+  it('xx', function() {
+    assert.equal(ISO6391.validate('xx'), false);
+  });
+  it('toString', function() {
+    assert.equal(ISO6391.validate('toString'), false);
+  });
+});
+
+describe('getLanguages()', function() {
+  it('[en, zh, xx, toString]', function() {
+    assert.deepEqual(ISO6391.getLanguages(['en', 'zh', 'xx', 'toString']), [
+      {
+        code: 'en',
+        name: 'English',
+        nativeName: 'English',
+      },
+      {
+        code: 'zh',
+        name: 'Chinese',
+        nativeName: '中文',
+      },
+      {
+        code: 'xx',
+        name: '',
+        nativeName: '',
+      },
+      {
+        code: 'toString',
+        name: '',
+        nativeName: '',
+      },
+    ]);
+  });
+});