feat(shared): add language adapter for picker integration

Author: fulleni

lib/shared/utils/language_adapter.dart

@@ -0,0 +1,28 @@
+import 'package:language_picker/languages.dart';
+
+/// Adapts a [Language] object from the `language_picker` package to a
+/// language code string (e.g., 'en', 'ar').
+///
+/// This is used to convert the selected language from the UI picker into the
+/// format expected by the `Source` model in the core package.
+String adaptPackageLanguageToLanguageCode(Language language) {
+  return language.isoCode;
+}
+
+/// Adapts a language code string (e.g., 'en', 'ar') to a [Language] object
+/// from the `language_picker` package.
+///
+/// This is used to convert the language code from a `Source` model into an
+/// object that can be used to set the initial value of the language picker.
+///
+/// Returns `null` if the language code is not found.
+Language? adaptLanguageCodeToPackageLanguage(String languageCode) {
+  try {
+    return Languages.defaultLanguages.firstWhere(
+      (lang) => lang.isoCode.toLowerCase() == languageCode.toLowerCase(),
+    );
+  } catch (_) {
+    // Return null if no matching language is found
+    return null;
+  }
+}