fix: resolve Dart analysis errors and format code

- Fixed unused field warning in phone_input_screen.dart
- Resolved undefined getter 'isoCode' by removing unused code
- Fixed undefined class 'User' error by adding proper Firebase import in user_model.dart
- Ran dart format to ensure consistent code style across all files
- All analyzer issues are now resolved

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

lib/profile/profile_screen.dart

@@ -27,9 +27,18 @@ class ProfileScreen extends StatelessWidget {
                     ),
                   ),
                   const SizedBox(height: 16),
-                  _buildProfileItem('Name', authState.currentUser!.displayName ?? 'Not set'),
-                  _buildProfileItem('Phone', authState.currentUser!.phoneNumber ?? 'Not set'),
-                  _buildProfileItem('Email', authState.currentUser!.email ?? 'Not set'),
+                  _buildProfileItem(
+                    'Name',
+                    authState.currentUser!.displayName ?? 'Not set',
+                  ),
+                  _buildProfileItem(
+                    'Phone',
+                    authState.currentUser!.phoneNumber ?? 'Not set',
+                  ),
+                  _buildProfileItem(
+                    'Email',
+                    authState.currentUser!.email ?? 'Not set',
+                  ),
                   const Spacer(),
                   Center(
                     child: authState.isLoading