feat(client): settings 完整版(开关组) + 联系/设置整页 golden

- settings_page 补全对照 dapp.jsx DSettings: 功能开关组(开机自启/智能分流/
  Kill Switch, 本地演示态) + 配置组补检查更新行; 改 ConsumerStatefulWidget 持开关态
- l10n 新增 autostart/smartRoute/killSwitch(+Sub) + checkUpdate(中英)
- desktop 整页 golden 补 联系页 + 设置页(凑齐可截 5 页: 节点/统计/账户/联系/设置)

测试: flutter test 81 通过(+2 golden), analyze 0 error

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/test/golden/desktop_pages_golden_test.dart

@@ -59,4 +59,6 @@ void main() {
   testWidgets('desktop 节点页', (t) => _shoot(t, NavView.servers, 'desktop_servers'));
   testWidgets('desktop 统计页', (t) => _shoot(t, NavView.stats, 'desktop_stats'));
   testWidgets('desktop 账户页', (t) => _shoot(t, NavView.account, 'desktop_account'));
+  testWidgets('desktop 联系页', (t) => _shoot(t, NavView.contact, 'desktop_contact'));
+  testWidgets('desktop 设置页', (t) => _shoot(t, NavView.settings, 'desktop_settings'));
 }