feat(client): SSO 用户中心按钮 + 自动更新检查(镜像 jiu)

SSO: web_launch.openWebUserCenter → POST /v1/auth/web-ticket → 打开 app.yanmeiai.com/sso?t=…;
设置页加「用户中心(网页)」入口。自动更新: update_provider 查 /version 语义比对 + update_dialog
「发现新版本」;设置页「检查更新」由空 onTap 接上。加 url_launcher(原缺)。flutter analyze 通过。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013nMthbVEmQquxBRKb9Fj8u

client/lib/screens/settings_page.dart

@@ -9,9 +9,29 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../l10n/app_text.dart';
 import '../pangolin_theme.dart';
+import '../services/web_launch.dart';
 import '../state/app_providers.dart';
 import '../state/settings_provider.dart';
+import '../state/update_provider.dart';
 import '../widgets/pangolin_icons.dart';
+import '../widgets/pangolin_toast.dart';
+import '../widgets/update_dialog.dart';
+
+/// 「检查更新」手动触发:拉取 `$kApiBaseUrl/version`,失败/无更新走轻提示,
+/// 有更新则弹 [showUpdateDialog]。
+Future<void> _checkForUpdate(BuildContext context, WidgetRef ref, AppText t) async {
+  final info = await ref.read(updateCheckerProvider).check();
+  if (!context.mounted) return;
+  if (info == null) {
+    showPangolinToast(context, t.updateCheckFailed);
+    return;
+  }
+  if (!info.hasUpdate) {
+    showPangolinToast(context, t.updateUpToDate);
+    return;
+  }
+  await showUpdateDialog(context, t, info);
+}
 
 class SettingsPage extends ConsumerWidget {
   const SettingsPage({super.key});
@@ -59,7 +79,8 @@ class SettingsPage extends ConsumerWidget {
               right: sw(isDark, (v) => ref.read(themeModeProvider.notifier).state = v ? ThemeMode.dark : ThemeMode.light),
             ),
             _Row(title: t.protocol, right: Text('REALITY / Hysteria2', style: PangolinText.mono.copyWith(fontSize: 13, color: c.fg3))),
-            _Row(title: t.checkUpdate, right: Icon(PangolinIcons.chevronRight, size: 18, color: c.fg3), onTap: () {}),
+            _Row(title: t.webUserCenter, right: Icon(PangolinIcons.externalLink, size: 18, color: c.fg3), onTap: () => openWebUserCenter(ref)),
+            _Row(title: t.checkUpdate, right: Icon(PangolinIcons.chevronRight, size: 18, color: c.fg3), onTap: () => _checkForUpdate(context, ref, t)),
             _Row(title: 'Version', last: true, right: Text(version, style: PangolinText.mono.copyWith(fontSize: 13, color: c.fg3))),
           ]),
         ]),