- UI display: display_name first

- Fallback: name
  - Technical identity: still name

  ### What changed

  - Added account display helpers and display_name state in user model:
      - flutter/lib/models/user_model.dart:16
  - Account/logout label now uses display_name (@name) when both exist:
      - flutter/lib/mobile/pages/settings_page.dart:689
      - flutter/lib/desktop/pages/desktop_setting_page.dart:2016
      - flutter/lib/desktop/pages/desktop_setting_page.dart:2135
  - Desktop Account info now shows both when applicable:
      - Display Name: ...
      - Username: ...
      - flutter/lib/desktop/pages/desktop_setting_page.dart:2039
  - Previously done group-list behavior remains:
      - group user list displays display_name with name fallback
      - flutter/lib/common/widgets/my_group.dart:187
  - Persistence path for display_name remains enabled (including group cache/submodule field):
      - libs/hbb_common/src/config.rs:2347
  - src/client.rs:2630
  - LoginRequest.my_name now resolves as:
      1. OPTION_DISPLAY_NAME (manual override)
      2. user_info.display_name
      3. user_info.name
      4. OS username fallback

flutter/lib/common/hbbs/hbbs.dart

@@ -25,6 +25,7 @@ enum UserStatus { kDisabled, kNormal, kUnverified }
 // Is all the fields of the user needed?
 class UserPayload {
   String name = '';
+  String displayName = '';
   String email = '';
   String note = '';
   String? verifier;
@@ -33,6 +34,7 @@ class UserPayload {
 
   UserPayload.fromJson(Map<String, dynamic> json)
       : name = json['name'] ?? '',
+        displayName = json['display_name'] ?? '',
         email = json['email'] ?? '',
         note = json['note'] ?? '',
         verifier = json['verifier'],
@@ -46,6 +48,7 @@ class UserPayload {
   Map<String, dynamic> toJson() {
     final Map<String, dynamic> map = {
       'name': name,
+      'display_name': displayName,
       'status': status == UserStatus.kDisabled
           ? 0
           : status == UserStatus.kUnverified
@@ -58,9 +61,14 @@ class UserPayload {
   Map<String, dynamic> toGroupCacheJson() {
     final Map<String, dynamic> map = {
       'name': name,
+      'display_name': displayName,
     };
     return map;
   }
+
+  String get displayNameOrName {
+    return displayName.trim().isEmpty ? name : displayName;
+  }
 }
 
 class PeerPayload {

flutter/lib/common/widgets/my_group.dart

@@ -158,9 +158,9 @@ class _MyGroupState extends State<MyGroup> {
     return Obx(() {
       final userItems = gFFI.groupModel.users.where((p0) {
         if (searchAccessibleItemNameText.isNotEmpty) {
-          return p0.name
-              .toLowerCase()
-              .contains(searchAccessibleItemNameText.value.toLowerCase());
+          final search = searchAccessibleItemNameText.value.toLowerCase();
+          return p0.name.toLowerCase().contains(search) ||
+              p0.displayNameOrName.toLowerCase().contains(search);
         }
         return true;
       }).toList();
@@ -187,6 +187,7 @@ class _MyGroupState extends State<MyGroup> {
 
   Widget _buildUserItem(UserPayload user) {
     final username = user.name;
+    final displayName = user.displayNameOrName;
     return InkWell(onTap: () {
       isSelectedDeviceGroup.value = false;
       if (selectedAccessibleItemName.value != username) {
@@ -229,7 +230,7 @@ class _MyGroupState extends State<MyGroup> {
                     ),
                   ),
                 ).marginOnly(right: 4),
-                if (isMe) Flexible(child: Text(username)),
+                if (isMe) Flexible(child: Text(displayName)),
                 if (isMe)
                   Flexible(
                     child: Container(
@@ -246,7 +247,7 @@ class _MyGroupState extends State<MyGroup> {
                       ),
                     ),
                   ),
-                if (!isMe) Expanded(child: Text(username)),
+                if (!isMe) Expanded(child: Text(displayName)),
               ],
             ).paddingSymmetric(vertical: 4),
           ),