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/screens/settings_page.dart

@@ -10,17 +10,30 @@ import '../pangolin_theme.dart';
 import '../state/app_providers.dart';
 import '../widgets/pangolin_icons.dart';
 
-class SettingsPage extends ConsumerWidget {
+class SettingsPage extends ConsumerStatefulWidget {
   const SettingsPage({super.key});
 
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
+  ConsumerState<SettingsPage> createState() => _SettingsPageState();
+}
+
+class _SettingsPageState extends ConsumerState<SettingsPage> {
+  // 本地演示态（暂无后端绑定），默认开，对照 dapp.jsx DSettings。
+  bool _autostart = true;
+  bool _smartRoute = true;
+  bool _killSwitch = true;
+
+  @override
+  Widget build(BuildContext context) {
     final c = context.pangolin;
     final t = ref.watch(appTextProvider);
     final lang = ref.watch(localeProvider);
     final mode = ref.watch(themeModeProvider);
     final isDark = mode == ThemeMode.dark;
 
+    Widget sw(bool v, ValueChanged<bool> on) =>
+        Switch(value: v, activeThumbColor: c.accent, onChanged: on);
+
     return SingleChildScrollView(
       padding: const EdgeInsets.fromLTRB(32, 16, 32, 24),
       child: ConstrainedBox(
@@ -32,19 +45,23 @@ class SettingsPage extends ConsumerWidget {
                 right: Icon(PangolinIcons.chevronRight, size: 18, color: c.fg3), onTap: () {}),
           ]),
           const SizedBox(height: 16),
+          // 功能开关组
+          _Card(children: [
+            _Row(title: t.autostart, sub: t.autostartSub, right: sw(_autostart, (v) => setState(() => _autostart = v))),
+            _Row(title: t.smartRoute, sub: t.smartRouteSub, right: sw(_smartRoute, (v) => setState(() => _smartRoute = v))),
+            _Row(title: t.killSwitch, sub: t.killSwitchSub, last: true, right: sw(_killSwitch, (v) => setState(() => _killSwitch = v))),
+          ]),
+          const SizedBox(height: 16),
           // 配置组
           _Card(children: [
             _Row(title: t.language, right: _LangSwitch(lang: lang, onPick: (l) => ref.read(localeProvider.notifier).state = l)),
             _Row(
               title: t.darkAppearance,
               sub: isDark ? t.stateOn : t.followLight,
-              right: Switch(
-                value: isDark,
-                activeThumbColor: c.accent,
-                onChanged: (v) => ref.read(themeModeProvider.notifier).state = v ? ThemeMode.dark : ThemeMode.light,
-              ),
+              right: sw(isDark, (v) => ref.read(themeModeProvider.notifier).state = v ? ThemeMode.dark : ThemeMode.light),
             ),
             _Row(title: t.protocol, right: Text('WireGuard', 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: 'Version', last: true, right: Text('v1.0.0', style: PangolinText.mono.copyWith(fontSize: 13, color: c.fg3))),
           ]),
         ]),