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/test/unit/nodes_provider_test.dart

@@ -3,26 +3,53 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:pangolin_vpn/l10n/app_text.dart';
 import 'package:pangolin_vpn/models/node.dart';
+import 'package:pangolin_vpn/services/token_store.dart';
+import 'package:pangolin_vpn/state/auth_provider.dart';
 import 'package:pangolin_vpn/state/nodes_provider.dart';
 
+// ── Stub TokenStore（无平台依赖）──────────────────────────────────
+
+class _NullTokenStore implements TokenStore {
+  const _NullTokenStore();
+  @override
+  Future<void> saveTokens({required String access, required String refresh}) async {}
+  @override
+  Future<String?> loadAccessToken() async => null;
+  @override
+  Future<String?> loadRefreshToken() async => null;
+  @override
+  Future<void> clear() async {}
+}
+
+// ── 辅助：带 stub 覆盖的 ProviderContainer ──────────────────────
+
+ProviderContainer makeContainer({List<Override> overrides = const []}) =>
+    ProviderContainer(overrides: [
+      tokenStoreProvider.overrideWithValue(const _NullTokenStore()),
+      // effectiveNodeProvider 在 nodesProvider 加载时退回 kDemoNodes，
+      // 所以测试直接读 effectiveNodeProvider，无需等待 nodesProvider.future。
+      ...overrides,
+    ]);
+
 void main() {
   test('默认智能选择(AUTO)', () {
-    final c = ProviderContainer();
+    final c = makeContainer();
     addTearDown(c.dispose);
     expect(c.read(selectedNodeCodeProvider), kSmartNodeCode);
     expect(c.read(isSmartSelectProvider), true);
   });
 
-  test('智能选择取延迟最小节点', () {
-    final c = ProviderContainer();
+  test('智能选择取延迟最小节点（退回 kDemoNodes）', () {
+    final c = makeContainer();
     addTearDown(c.dispose);
+    // nodesProvider 加载中时退回 kDemoNodes，effectiveNodeProvider 立即可用。
     final node = c.read(effectiveNodeProvider);
     final minPing = kDemoNodes.map((n) => n.ping).reduce((a, b) => a < b ? a : b);
     expect(node.ping, minPing);
   });
 
   test('选中具体节点后生效节点随之改变', () {
-    final c = ProviderContainer();
+    final c = makeContainer();
     addTearDown(c.dispose);
     c.read(selectedNodeCodeProvider.notifier).state = 'JP';
     expect(c.read(isSmartSelectProvider), false);