fix: remove font_awesome_flutter (incompatible with Dart 3.12)

Replace FaIcon(FontAwesomeIcons.google) with plain Text widget.
Remove font_awesome_flutter from pubspec — package extends final
class IconData which is forbidden in Dart 3.12/Flutter 3.44.
Fix currentUser.value → currentUser (was Rx<UserModel?>, now UserModel?).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/src/presentation/screens/map/service.dart

@@ -102,7 +102,7 @@ class _ServiceScreenState extends State<ServiceScreen> {
     getLocationUpdates();
 
     // Load user name from in-memory currentUser
-    final authUser = AuthenticationRepository.instance.currentUser.value;
+    final authUser = AuthenticationRepository.instance.currentUser;
     if (authUser != null && authUser.name.isNotEmpty) {
       _nameController.text = authUser.name;
     }