feat(shared): create language picker and export shared components

Author: fulleni

lib/shared/utils/utils.dart

@@ -1 +1,2 @@
 export 'country_adapter.dart';
+export 'language_adapter.dart';

lib/shared/widgets/language_picker_form_field.dart

@@ -0,0 +1,57 @@
+import 'package:flutter/material.dart';
+import 'package:language_picker/language_picker.dart';
+import 'package:language_picker/languages.dart';
+
+/// A form field for selecting a language using the `language_picker` package.
+///
+/// This widget wraps the language picker functionality in a standard
+/// [FormField], making it easy to integrate into forms for validation
+/// and state management. It presents as a read-only [TextFormField] that,
+/// when tapped, opens a language selection dialog.
+class LanguagePickerFormField extends FormField<Language> {
+  /// Creates a [LanguagePickerFormField].
+  ///
+  /// The [onSaved], [validator], [initialValue], and [autovalidateMode] are
+  /// standard [FormField] properties.
+  ///
+  /// The [labelText] is displayed as the input field's label.
+  LanguagePickerFormField({
+    super.key,
+    super.onSaved,
+    super.validator,
+    super.initialValue,
+    super.autovalidateMode,
+    String? labelText,
+  }) : super(
+          builder: (FormFieldState<Language> state) {
+            // This controller is just for displaying the text. The actual
+            // value is managed by the FormField's state.
+            final controller = TextEditingController(
+              text: state.value?.name,
+            );
+
+            return TextFormField(
+              controller: controller,
+              readOnly: true,
+              decoration: InputDecoration(
+                labelText: labelText ?? 'Language',
+                border: const OutlineInputBorder(),
+                errorText: state.errorText,
+                suffixIcon: const Icon(Icons.arrow_drop_down),
+              ),
+              onTap: () {
+                showLanguagePicker(
+                  context: state.context,
+                  // Provide a default if no language is selected yet.
+                  selectedLanguage: state.value ?? Languages.english,
+                  onValuePicked: (Language language) {
+                    state.didChange(language);
+                    // Update the text in the read-only text field.
+                    controller.text = language.name;
+                  },
+                );
+              },
+            );
+          },
+        );
+}

lib/shared/widgets/widgets.dart

@@ -1 +1,2 @@
 export 'country_picker_form_field.dart';
+export 'language_picker_form_field.dart';