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/screens/connect_page.dart

@@ -1,7 +1,8 @@
-// connect_page.dart — 连接页(窄屏单栏 / 宽屏双栏,同一份代码按断点切换)
+// connect_page.dart — 连接页(三端：desktop 居中单列 / tablet 双栏 / mobile 单列滚动)
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
+import '../core/responsive/form_factor.dart';
 import '../l10n/app_text.dart';
 import '../models/node.dart';
 import '../pangolin_theme.dart';
@@ -63,6 +64,42 @@ class ConnectPage extends ConsumerWidget {
           fontWeight: FontWeight.w600),
     );
 
+    if (context.formFactor == FormFactor.desktop) {
+      // 桌面居中单列（对照 ui_kits/desktop/dapp.jsx DConnect）
+      return Center(
+        child: SingleChildScrollView(
+          padding: const EdgeInsets.symmetric(vertical: 24, horizontal: 40),
+          child: Column(mainAxisSize: MainAxisSize.min, children: [
+            ConnectButton(
+              phase: conn.phase,
+              elapsed: conn.elapsed,
+              offLabel: t.connectNow,
+              secureLabel: t.secure,
+              size: 176,
+              onTap: () => ref.read(connectionProvider.notifier).toggle(),
+            ),
+            const SizedBox(height: 24),
+            Text(caption,
+                textAlign: TextAlign.center,
+                style: PangolinText.display.copyWith(color: c.fg1, fontSize: 22, fontWeight: FontWeight.w700)),
+            const SizedBox(height: 10),
+            _NodePill(t: t, node: node, smart: smart),
+            if (isFree) ...[
+              const SizedBox(height: 24),
+              SizedBox(
+                width: 340,
+                child: QuotaCard(quota: quota, t: t, onWatchAd: () => ref.read(quotaProvider.notifier).watchAd()),
+              ),
+            ],
+            if (conn.phase == VpnPhase.on) ...[
+              const SizedBox(height: 16),
+              _SpeedRow(t: t, node: node),
+            ],
+          ]),
+        ),
+      );
+    }
+
     if (isWide) {
       // 宽屏双栏:左大连接键 / 右信息列(额度卡→当前节点→速率)
       return Column(children: [
@@ -97,24 +134,42 @@ class ConnectPage extends ConsumerWidget {
       ]);
     }
 
-    // 窄屏单栏
+    // 窄屏单栏（可滚动，避免窗口偏矮时底部溢出）：
+    // 顶栏固定，内容区用 SingleChildScrollView + ConstrainedBox(minHeight) +
+    // IntrinsicHeight，高度足够时连接键居中，高度不足时整体滚动而非溢出。
     return Column(children: [
       AppTopBar(brand: t.brand, trailing: statusTrailing),
       Expanded(
-        child: Center(
-          child: Column(mainAxisSize: MainAxisSize.min, children: [
-            button,
-            const SizedBox(height: 24),
-            captionWidget,
-          ]),
+        child: LayoutBuilder(
+          builder: (context, constraints) => SingleChildScrollView(
+            child: ConstrainedBox(
+              constraints: BoxConstraints(minHeight: constraints.maxHeight),
+              child: IntrinsicHeight(
+                child: Column(children: [
+                  Expanded(
+                    child: Center(
+                      child: Padding(
+                        padding: const EdgeInsets.symmetric(vertical: 24),
+                        child: Column(mainAxisSize: MainAxisSize.min, children: [
+                          button,
+                          const SizedBox(height: 24),
+                          captionWidget,
+                        ]),
+                      ),
+                    ),
+                  ),
+                  Padding(
+                    padding: const EdgeInsets.fromLTRB(20, 0, 20, 18),
+                    child: Column(crossAxisAlignment: CrossAxisAlignment.stretch, children: [
+                      for (final w in infoChildren) Padding(padding: const EdgeInsets.only(bottom: 12), child: w),
+                    ]),
+                  ),
+                ]),
+              ),
+            ),
+          ),
         ),
       ),
-      Padding(
-        padding: const EdgeInsets.fromLTRB(20, 0, 20, 18),
-        child: Column(crossAxisAlignment: CrossAxisAlignment.stretch, children: [
-          for (final w in infoChildren) Padding(padding: const EdgeInsets.only(bottom: 12), child: w),
-        ]),
-      ),
     ]);
   }
 }
@@ -229,3 +284,32 @@ class _CurrentNodeCard extends StatelessWidget {
     );
   }
 }
+
+/// 桌面连接页节点胶囊（[zap] 智能选择 · 节点名 · 延迟ms）。
+class _NodePill extends StatelessWidget {
+  const _NodePill({required this.t, required this.node, required this.smart});
+  final AppText t;
+  final Node node;
+  final bool smart;
+
+  @override
+  Widget build(BuildContext context) {
+    final c = context.pangolin;
+    final label = smart
+        ? '${t.smartSelect} · ${node.localizedName(t.lang)} · ${node.ping}ms'
+        : '${node.localizedName(t.lang)} · ${node.ping}ms';
+    return Container(
+      padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 6),
+      decoration: BoxDecoration(
+        color: c.surface,
+        border: Border.all(color: c.border),
+        borderRadius: BorderRadius.circular(PangolinRadius.full),
+      ),
+      child: Row(mainAxisSize: MainAxisSize.min, children: [
+        if (smart) ...[Icon(PangolinIcons.zap, size: 13, color: c.accent), const SizedBox(width: 7)],
+        Text(label,
+            style: PangolinText.caption.copyWith(color: c.fg2, fontSize: 12.5, fontWeight: FontWeight.w600)),
+      ]),
+    );
+  }
+}