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/lib/l10n/strings_zh.dart

@@ -124,6 +124,20 @@ class StringsZh extends AppText {
   String get protocol => '协议';
   @override
   String get settingsTitle => '设置';
+  @override
+  String get autostart => '开机自启';
+  @override
+  String get autostartSub => '系统启动时自动运行';
+  @override
+  String get smartRoute => '智能分流';
+  @override
+  String get smartRouteSub => '海外应用走加速,国内直连';
+  @override
+  String get killSwitch => 'Kill Switch';
+  @override
+  String get killSwitchSub => '断线时阻断网络,防止泄露';
+  @override
+  String get checkUpdate => '检查更新';
 
   @override
   String get choosePlan => '选择套餐';