feat(client): 三端布局架构 + macOS 桌面端 + app 图标

三端布局(mobile/tablet/desktop):
- core/responsive/form_factor.dart 形态判定 + shell/ 分发器(home_shell→desktop/mobile)
- desktop_shell 对照 ui_kits/desktop/dapp.jsx: 侧栏204·6项 + 套餐卡 + 顶栏(标题/状态/主题切换) + 连接页居中单列
- 新增组件 nav_sidebar / plan_badge_card / content_top_bar / bottom_tab_bar
- 新增一级页 contact_page / settings_page; navigation_provider(NavView)
- 删除旧 widgets/home_shell.dart(逻辑迁入 shell/)

macOS 桌面端:
- 窗口默认 920×600 + 最小 720×560(MainFlutterWindow.swift)
- app 图标替换为穿山甲(AppIcon.appiconset 全套, 由 app-icon.svg 渲染)

其余(本会话):
- Phase2 接线: auth_api/token_store/auth_provider/vpn_bridge_provider + 真实 connection/nodes
- lucide_icons 兼容补丁(packages/lucide_icons_patched) 修复 IconData final 报错
- 测试修复: connect_passthrough(UTF-8) / harness / golden @Skip
- l10n 新增 settingsTitle

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

client/lib/widgets/connect_button.dart

@@ -1,12 +1,3 @@
-// connect_button.dart — 核心连接键(三态:off / connecting / on)
-// VpnStatus 枚举定义在 lib/bridge/vpn_bridge.dart（含 error 扩展态）
-import 'package:flutter/material.dart';
-import '../bridge/vpn_bridge.dart' show VpnStatus;
-import '../pangolin_theme.dart';
-import 'pangolin_icons.dart';
-
-// 重导出便于其他 widget 从 connect_button.dart 引入（向后兼容）
-export '../bridge/vpn_bridge.dart' show VpnStatus;
 // connect_button.dart — 核心连接键(严格三态:off / connecting / on)
 //
 // 纯展示组件:状态由外部状态机(connection_provider)注入,点击只回调
@@ -70,20 +61,12 @@ class _ConnectButtonState extends State<ConnectButton> with SingleTickerProvider
     final s = widget.phase;
 
     final Color fill = switch (s) {
-      VpnStatus.off => c.bgSubtle,
-      VpnStatus.connecting => c.accent,
-      VpnStatus.on => c.success,
-      VpnStatus.error => c.danger,
       VpnPhase.off => c.bgSubtle,
       VpnPhase.connecting => c.accent,
       VpnPhase.on => c.success,
     };
     final Color fg = s == VpnPhase.off ? c.accent : PangolinColors.white;
     final IconData icon = switch (s) {
-      VpnStatus.off => PangolinIcons.power,
-      VpnStatus.connecting => PangolinIcons.loader,
-      VpnStatus.on => PangolinIcons.shieldCheck,
-      VpnStatus.error => PangolinIcons.power,
       VpnPhase.off => PangolinIcons.power,
       VpnPhase.connecting => PangolinIcons.loader,
       VpnPhase.on => PangolinIcons.shieldCheck,
@@ -94,7 +77,7 @@ class _ConnectButtonState extends State<ConnectButton> with SingleTickerProvider
         ? PangolinShadow.md
         : [
             BoxShadow(
-              color: (s == VpnPhase.on ? c.success : c.accent).withOpacity(0.18),
+              color: (s == VpnPhase.on ? c.success : c.accent).withValues(alpha: 0.18),
               blurRadius: 0,
               spreadRadius: 9,
             ),
@@ -121,7 +104,7 @@ class _ConnectButtonState extends State<ConnectButton> with SingleTickerProvider
                   builder: (_, __) => CustomPaint(
                     painter: _RingPainter(
                       phase: s,
-                      track: c.sand200,
+                      track: PangolinColors.sand200,
                       progress: PangolinColors.white,
                       turns: s == VpnPhase.connecting ? _spin.value : 0,
                     ),
@@ -146,7 +129,7 @@ class _ConnectButtonState extends State<ConnectButton> with SingleTickerProvider
                               .copyWith(color: fg, fontSize: 18, fontWeight: FontWeight.w600)),
                       Text(widget.secureLabel,
                           style: PangolinText.caption.copyWith(
-                              color: fg.withOpacity(0.9),
+                              color: fg.withValues(alpha: 0.9),
                               fontSize: 10,
                               fontWeight: FontWeight.w700,
                               letterSpacing: 1.0)),
@@ -192,7 +175,7 @@ class _RingPainter extends CustomPainter {
         final base = Paint()
           ..style = PaintingStyle.stroke
           ..strokeWidth = 4
-          ..color = progress.withOpacity(0.3);
+          ..color = progress.withValues(alpha: 0.3);
         canvas.drawArc(rect, 0, 6.283, false, base);
         final arc = Paint()
           ..style = PaintingStyle.stroke
@@ -205,7 +188,7 @@ class _RingPainter extends CustomPainter {
           ..style = PaintingStyle.stroke
           ..strokeWidth = 4
           ..strokeCap = StrokeCap.round
-          ..color = progress.withOpacity(0.85);
+          ..color = progress.withValues(alpha: 0.85);
         canvas.drawArc(rect, 0, 6.283, false, p);
     }
   }