fix(client): 联系/购买渠道卡点击外部打开(修空 onTap)+ 桌面账户子导航复现测试

- channel_launch: @→t.me / 邮箱→mailto / 域名→https,外部打开
- 联系页(桌面)/联系&兑换子页(移动)渠道卡接上 onTap
- account_desktop_nav_test: 证明桌面设置/兑换/联系/订单导航正常(231 全绿)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013nMthbVEmQquxBRKb9Fj8u

client/lib/screens/contact_page.dart

@@ -7,6 +7,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../l10n/app_text.dart';
 import '../pangolin_theme.dart';
+import '../services/channel_launch.dart';
 import '../state/app_providers.dart';
 import '../widgets/pangolin_icons.dart';
 
@@ -50,7 +51,9 @@ class _ChannelCard extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final c = context.pangolin;
-    return Container(
+    return GestureDetector(
+      onTap: () => launchChannel(channel.sub),
+      child: Container(
       padding: const EdgeInsets.all(14),
       decoration: BoxDecoration(
         color: c.surface,
@@ -77,7 +80,7 @@ class _ChannelCard extends StatelessWidget {
         ),
         Icon(PangolinIcons.chevronRight, size: 18, color: c.fg3),
       ]),
-    );
+    ));
   }
 }
 

client/lib/services/channel_launch.dart

@@ -0,0 +1,21 @@
+// channel_launch.dart — 联系/购买渠道点击:按 handle(sub)推导 URL 并外部打开。
+//   @xxx        → https://t.me/xxx (Telegram)
+//   a@b.com     → mailto:a@b.com
+//   x.yanmei... → https://x.yanmei...
+import 'package:url_launcher/url_launcher.dart';
+
+String channelUrl(String sub) {
+  if (sub.startsWith('@')) return 'https://t.me/${sub.substring(1)}';
+  if (sub.contains('@')) return 'mailto:$sub';
+  return 'https://$sub';
+}
+
+/// 点击渠道卡:外部打开对应 URL。失败静默(不炸 UI)。
+Future<void> launchChannel(String sub) async {
+  final uri = Uri.parse(channelUrl(sub));
+  try {
+    if (await canLaunchUrl(uri)) {
+      await launchUrl(uri, mode: LaunchMode.externalApplication);
+    }
+  } catch (_) {}
+}

client/lib/widgets/account_screens.dart

@@ -10,6 +10,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../l10n/app_text.dart';
 import '../models/device.dart';
 import '../pangolin_theme.dart';
+import '../services/channel_launch.dart';
 import '../screens/settings_page.dart';
 import '../services/device_identity.dart';
 import 'adaptive_menu.dart';
@@ -429,7 +430,7 @@ class _RedeemScreenState extends ConsumerState<RedeemScreen> {
   Widget _channel(PangolinScheme c, IconData icon, String name, String sub, bool accent) {
     return InkWell(
       borderRadius: BorderRadius.circular(PangolinRadius.lg),
-      onTap: () {},
+      onTap: () => launchChannel(sub),
       child: Container(
         padding: const EdgeInsets.all(14),
         decoration: BoxDecoration(color: accent ? c.accentSubtle : c.surface, borderRadius: BorderRadius.circular(PangolinRadius.lg), border: Border.all(color: accent ? c.accentBorder : c.border), boxShadow: PangolinShadow.sm),
@@ -486,7 +487,7 @@ class ContactScreen extends StatelessWidget {
   Widget _contact(PangolinScheme c, IconData icon, String name, String sub, bool accent) {
     return InkWell(
       borderRadius: BorderRadius.circular(PangolinRadius.lg),
-      onTap: () {},
+      onTap: () => launchChannel(sub),
       child: Container(
         padding: const EdgeInsets.all(14),
         decoration: BoxDecoration(color: accent ? c.accentSubtle : c.surface, borderRadius: BorderRadius.circular(PangolinRadius.lg), border: Border.all(color: accent ? c.accentBorder : c.border), boxShadow: PangolinShadow.sm),