fix: replace first and last name with single field (#4915)

mobile/lib/shared/ui/app_bar_dialog/app_bar_profile_info.dart

@@ -132,7 +132,7 @@ class AppBarProfileInfoBox extends HookConsumerWidget {
             ),
           ),
           title: Text(
-            "${authState.firstName} ${authState.lastName}",
+            authState.name,
             style: TextStyle(
               color: context.primaryColor,
               fontWeight: FontWeight.bold,

mobile/lib/shared/ui/user_avatar.dart

@@ -7,8 +7,7 @@ import 'package:immich_mobile/shared/models/user.dart';
 Widget userAvatar(BuildContext context, User u, {double? radius}) {
   final url =
       "${Store.get(StoreKey.serverEndpoint)}/user/profile-image/${u.id}";
-  final firstNameFirstLetter = u.firstName.isNotEmpty ? u.firstName[0] : "";
-  final lastNameFirstLetter = u.lastName.isNotEmpty ? u.lastName[0] : "";
+  final nameFirstLetter = u.name.isNotEmpty ? u.name[0] : "";
   return CircleAvatar(
     radius: radius,
     backgroundColor: context.primaryColor.withAlpha(50),
@@ -19,6 +18,6 @@ Widget userAvatar(BuildContext context, User u, {double? radius}) {
     ),
     // silence errors if user has no profile image, use initials as fallback
     onForegroundImageError: (exception, stackTrace) {},
-    child: Text((firstNameFirstLetter + lastNameFirstLetter).toUpperCase()),
+    child: Text(nameFirstLetter.toUpperCase()),
   );
 }

mobile/lib/shared/ui/user_circle_avatar.dart

@@ -43,7 +43,7 @@ class UserCircleAvatar extends ConsumerWidget {
         '${Store.get(StoreKey.serverEndpoint)}/user/profile-image/${user.id}?d=${Random().nextInt(1024)}';
 
     final textIcon = Text(
-      user.firstName[0].toUpperCase(),
+      user.name[0].toUpperCase(),
       style: TextStyle(
         fontWeight: FontWeight.bold,
         color: context.isDarkTheme ? Colors.black : Colors.white,