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/login/login_email.dart

@@ -1,6 +1,5 @@
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
-import 'package:font_awesome_flutter/font_awesome_flutter.dart';
 import 'package:prosappco/src/authentication/authentication_repository.dart';
 import 'package:prosappco/src/components/bottom_sheet.dart';
 import 'package:prosappco/src/presentation/widgets/shared/primary_button.dart';
@@ -113,7 +112,7 @@ class _LoginEmailScreenState extends State<LoginEmailScreen> {
                                     ),
                                   ),
                                   SizedBox(width: 5),
-                                  FaIcon(FontAwesomeIcons.google),
+                                  const Text('G', style: TextStyle(color: Colors.white, fontWeight: FontWeight.bold, fontSize: 18)),
                                 ],
                               )),
                         )