feat(devices): P2 sessions 表 + 在线/最后登录/客户端版本

migration 000016(mysql+sqlite,含 down):新增 sessions 表(绑 device+refresh JTI)
+ devices 加 client_version/totp_trusted_until。devices 唯一键改 + platform CHECK
加 linux(需 SQLite 表重建)拆出后续迁移,降风险。

后端:新 internal/sessions Store(Create/Rotate/Revoke/RevokeByDevice/
LastLoginByDevice);TokenManager 外露 refresh JTI(IssueWithJTI/RefreshWithJTI/
ParseRefreshJTI);auth.Service 注入 SessionStore——登录建会话、刷新轮换、登出吊销;
DeviceRegistrar 返回 deviceID;ReportUsage 心跳 touch devices.last_seen(在线判定);
devices.ListDevices 经 LastLoginSource 注入返回 online(last_seen<3min)/client_version/
last_login;RegisterIfAbsent 存 client_version。
客户端:Device model 加 online/clientVersion/lastLogin(fromJson 自动解析)。
测试:sessions store 3 例 + ListDevices 在线/最后登录 + device model 2 例 +
migration v16;全量 go test/flutter test 绿。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/lib/models/device.dart

@@ -5,24 +5,43 @@ class Device {
     required this.name,
     required this.platform,
     this.lastSeen,
+    this.clientVersion = '',
+    this.online = false,
+    this.lastLogin,
   });
 
   final String uuid;
   final String name;
 
-  /// 'ios' | 'android' | 'windows' | 'macos'。
+  /// 'ios' | 'android' | 'windows' | 'macos' | 'linux'。
   final String platform;
 
   /// 最近活跃(UTC);从未上线为 null。
   final DateTime? lastSeen;
 
+  /// 客户端版本(该设备最近上报),可能为空。
+  final String clientVersion;
+
+  /// 在线(数据面活跃,last_seen 在阈值内,由服务端判定)。
+  final bool online;
+
+  /// 最后登录时间(最近一次会话创建,UTC);无会话为 null。
+  final DateTime? lastLogin;
+
   factory Device.fromJson(Map<String, dynamic> m) {
-    final ls = m['last_seen'] as String?;
+    DateTime? parseTs(String key) {
+      final s = m[key] as String?;
+      return (s != null && s.isNotEmpty) ? DateTime.tryParse(s) : null;
+    }
+
     return Device(
       uuid: m['uuid'] as String? ?? '',
       name: m['name'] as String? ?? '',
       platform: m['platform'] as String? ?? '',
-      lastSeen: (ls != null && ls.isNotEmpty) ? DateTime.tryParse(ls) : null,
+      lastSeen: parseTs('last_seen'),
+      clientVersion: m['client_version'] as String? ?? '',
+      online: m['online'] as bool? ?? false,
+      lastLogin: parseTs('last_login'),
     );
   }
 }

client/test/unit/device_model_test.dart

@@ -0,0 +1,30 @@
+// device_model_test.dart — Device.fromJson 解析 online/client_version/last_login
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pangolin_vpn/models/device.dart';
+
+void main() {
+  test('解析全字段', () {
+    final d = Device.fromJson({
+      'uuid': 'd1',
+      'name': 'MacBook Pro',
+      'platform': 'macos',
+      'last_seen': '2026-06-28T10:00:00Z',
+      'client_version': 'v1.0.10',
+      'online': true,
+      'last_login': '2026-06-28T09:00:00Z',
+    });
+    expect(d.uuid, 'd1');
+    expect(d.online, isTrue);
+    expect(d.clientVersion, 'v1.0.10');
+    expect(d.lastLogin, DateTime.utc(2026, 6, 28, 9));
+    expect(d.lastSeen, DateTime.utc(2026, 6, 28, 10));
+  });
+
+  test('缺省:online=false,版本空,last_login=null', () {
+    final d = Device.fromJson({'uuid': 'd2', 'name': 'PC', 'platform': 'windows'});
+    expect(d.online, isFalse);
+    expect(d.clientVersion, '');
+    expect(d.lastLogin, isNull);
+    expect(d.lastSeen, isNull);
+  });
+}