feat: 旅行伙伴发放与编组、修复退登卡死、优化宽屏布局、加 CI

自动退出登录卡死：_performLogoutAndExit 只 pop() 一层，而解锁/收藏品页是 push
在 HomePage 之上的，退登后被弹回「风险」hub，同时 _loggingOut 仍为 true，
PopScope(canPop:false) + 返回键转圈形成死局。改为 popUntil(isFirst)。

旅行伙伴发不了：它是 ItemKind.Character = 9，与搭档 Partner = 10 是两种东西，
原先收藏品的类型列表 [1,2,3,10,11,12] 里根本没有 9。按客户端实现，角色不走
userItemList(ExportUserItems 不导出 itemKind 9)，而是
upsertUserAll.userCharacterList 的 {characterId, level, awakening, useCount}，
配 isNewCharacterList 一行一字符。新增发放与 5 槽 charaSlot 编组页，
含「把槽 0 复制到其他槽位」，并校验所选角色确为已拥有或本次待发放。

宽屏布局：各页只有 ConstrainedBox 限宽、没有居中容器，1440 窗口下内容贴左、
右侧大片空白。抽出 responsiveBody 统一居中；B50 预览改用按宽度适配
(InteractiveViewer constrained:false + FittedBox fitWidth)，横屏下不再被
contain 缩成中间一小块，导出仍是原始 1762x1850。

CI：.github/workflows/build.yml 先跑 analyze+test 作为门槛，再产出
Windows exe、Android apk、iOS 未签名 ipa(macOS runner，无证书故不可安装)。
README 从 Flutter 模板改写为实际文档，含 path_provider/jni 与 JBR jlink
两个构建环境坑的说明。

lib/services/title_api_service.dart

@@ -9,6 +9,7 @@ import 'package:pointycastle/export.dart';
 
 import '../config/title_server_config.dart';
 import '../models/user_data.dart';
+import '../models/user_character.dart';
 import '../models/user_preview.dart';
 import '../models/user_rating.dart';
 
@@ -557,6 +558,16 @@ class TitleApiService {
     final list = json['userCharacterList'] as List<dynamic>? ?? [];
     return list.map((e) => e as Map<String, dynamic>).toList();
   }
+
+  /// 旅行伙伴（角色）列表，对应 UserCharacterResponseVO。
+  Future<List<UserCharacterBean>> getUserCharacters(int userId) async {
+    final json = await _callApi(
+      'GetUserCharacterApi',
+      {'userId': userId},
+      userId,
+    );
+    return UserCharacterBean.listFromResponse(json);
+  }
 }
 
 class _RandomHelper {

lib/services/user_all_payload_builder.dart

@@ -1,4 +1,5 @@
 import '../config/title_server_config.dart';
+import '../models/user_character.dart';
 import 'title_api_service.dart';
 
 /// Dart port of `eaquira/src/sdgb/payload.py::UserAll_payload` and
@@ -356,27 +357,46 @@ class UserAllPayloadBuilder {
     upsert['isNewItemList'] = List.filled(items.length, '1').join();
   }
 
-  /// Port of `music_user_all_patcher`: append unlock items
-  /// (itemKind 5=music, 6=master, 7=remaster) to the packet.
-  void applyMusicUnlockPatch(
+  /// 解锁歌曲/谱面时补一条 musicDetail 记录并标记为新增。
+  /// 难度本身由 userItemList 的 itemKind 5/6/7 行表达（见客户端
+  /// VOExtensions.ExportUserItems），不写在 musicDetail 上。
+  void applyMusicDetailPatch(
     Map<String, dynamic> packet, {
     required Map<String, dynamic> musicData,
-    required int musicId,
-    bool unlockMusic = false,
-    bool unlockMaster = false,
-    bool unlockRemaster = false,
   }) {
-    applyItemListPatch(packet, items: [
-      if (unlockMusic)
-        {'itemKind': 5, 'itemId': musicId, 'stock': 1, 'isValid': true},
-      if (unlockMaster)
-        {'itemKind': 6, 'itemId': musicId, 'stock': 1, 'isValid': true},
-      if (unlockRemaster)
-        {'itemKind': 7, 'itemId': musicId, 'stock': 1, 'isValid': true},
-    ]);
-
     final upsert = packet['upsertUserAll'] as Map<String, dynamic>;
     upsert['userMusicDetailList'] = [musicData];
     upsert['isNewMusicDetailList'] = '1';
   }
+
+  /// 发放/更新旅行伙伴：写 `userCharacterList` 并按行数生成 `isNewCharacterList`。
+  /// 客户端 BuildListData 只发增量、每位一个字符，所以这里只放要新增的行。
+  void applyCharacterListPatch(
+    Map<String, dynamic> packet, {
+    required List<Map<String, dynamic>> characters,
+  }) {
+    final upsert = packet['upsertUserAll'] as Map<String, dynamic>;
+    upsert['userCharacterList'] = characters;
+    upsert['isNewCharacterList'] = List.filled(characters.length, '1').join();
+  }
+
+  /// 编组旅行伙伴：改 `userData[0].charaSlot`（int[5]，槽 0 为队长）。
+  /// 客户端 ExportUserPlaylog 用同一份 CharaSlot 填 playlog 的
+  /// characterId1..5，这里一起同步，避免 playlog 与 userData 互相矛盾。
+  void applyCharaSlotPatch(
+    Map<String, dynamic> packet, {
+    required List<int> charaSlot,
+  }) {
+    final slots = normalizeCharaSlot(charaSlot);
+    final upsert = packet['upsertUserAll'] as Map<String, dynamic>;
+    final userDataList = upsert['userData'] as List;
+    (userDataList.first as Map<String, dynamic>)['charaSlot'] = slots;
+
+    for (final raw in (packet['userPlaylogList'] as List)) {
+      final playlog = raw as Map<String, dynamic>;
+      for (var i = 0; i < 5; i++) {
+        playlog['characterId${i + 1}'] = slots[i];
+      }
+    }
+  }
 }