feat(client): tablet 外壳 + 视觉 diff 工作流文档

- tablet_shell: 侧栏 232·4 项触控(minHeight 48, 字号 15) + 顶栏无主题切换 + 连接页双栏
  对照 ui_kits/tablet/tabapp.jsx；home_shell 分发 tablet→TabletShell
- nav_sidebar 加 dense 参数(desktop 紧凑 / tablet 触控)
- content_top_bar 加 showThemeToggle + titleSize 参数
- tool/visual-diff.md: 截图 diff 工作流(design-distill 工具)+ 实现侧三路径
  现状(golden 被 google_fonts 阻塞 / screencapture 受 macOS chrome 限制)+ 推荐

注: tablet 形态在 macOS 桌面平台不触发(只 desktop/mobile)，运行验证需 iPad。

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

client/lib/widgets/content_top_bar.dart

@@ -12,10 +12,12 @@ import '../state/nodes_provider.dart';
 import 'pangolin_icons.dart';
 
 class ContentTopBar extends ConsumerWidget {
-  const ContentTopBar({super.key, required this.title, this.onBack});
+  const ContentTopBar({super.key, required this.title, this.onBack, this.showThemeToggle = true, this.titleSize = 17});
 
   final String title;
   final VoidCallback? onBack;
+  final bool showThemeToggle;
+  final double titleSize;
 
   @override
   Widget build(BuildContext context, WidgetRef ref) {
@@ -40,7 +42,7 @@ class ContentTopBar extends ConsumerWidget {
           const SizedBox(width: 4),
         ],
         Text(title,
-            style: PangolinText.h3.copyWith(color: c.fg1, fontWeight: FontWeight.w700, fontSize: 17)),
+            style: PangolinText.h3.copyWith(color: c.fg1, fontWeight: FontWeight.w700, fontSize: titleSize)),
         const Spacer(),
         Text(
           conn.phase == VpnPhase.on ? '● ${node.code}' : '○',
@@ -50,16 +52,18 @@ class ContentTopBar extends ConsumerWidget {
             color: conn.phase == VpnPhase.on ? c.success : c.fg3,
           ),
         ),
-        const SizedBox(width: 12),
-        InkWell(
-          onTap: () => ref.read(themeModeProvider.notifier).state =
-              isDark ? ThemeMode.light : ThemeMode.dark,
-          borderRadius: BorderRadius.circular(PangolinRadius.sm),
-          child: Padding(
-            padding: const EdgeInsets.all(6),
-            child: Icon(isDark ? PangolinIcons.sun : PangolinIcons.moon, size: 18, color: c.fg2),
+        if (showThemeToggle) ...[
+          const SizedBox(width: 12),
+          InkWell(
+            onTap: () => ref.read(themeModeProvider.notifier).state =
+                isDark ? ThemeMode.light : ThemeMode.dark,
+            borderRadius: BorderRadius.circular(PangolinRadius.sm),
+            child: Padding(
+              padding: const EdgeInsets.all(6),
+              child: Icon(isDark ? PangolinIcons.sun : PangolinIcons.moon, size: 18, color: c.fg2),
+            ),
           ),
-        ),
+        ],
       ]),
     );
   }

client/lib/widgets/nav_sidebar.dart

@@ -15,11 +15,14 @@ import 'plan_badge_card.dart';
 typedef NavSidebarItem = ({IconData icon, String label, NavView view});
 
 class NavSidebar extends ConsumerWidget {
-  const NavSidebar({super.key, required this.items, this.width = 204});
+  const NavSidebar({super.key, required this.items, this.width = 204, this.dense = true});
 
   final List<NavSidebarItem> items;
   final double width;
 
+  /// dense=true 桌面紧凑(行高~36)；dense=false 平板触控(行高≥48, 字号更大)。
+  final bool dense;
+
   @override
   Widget build(BuildContext context, WidgetRef ref) {
     final c = context.pangolin;
@@ -32,17 +35,18 @@ class NavSidebar extends ConsumerWidget {
         color: c.bgSubtle,
         border: Border(right: BorderSide(color: c.border)),
       ),
-      padding: const EdgeInsets.fromLTRB(12, 14, 12, 14),
+      padding: EdgeInsets.fromLTRB(dense ? 12 : 14, dense ? 14 : 18, dense ? 12 : 14, dense ? 14 : 16),
       child: Column(crossAxisAlignment: CrossAxisAlignment.stretch, children: [
         // 品牌区
         Padding(
-          padding: const EdgeInsets.fromLTRB(6, 2, 6, 16),
+          padding: EdgeInsets.fromLTRB(6, 2, 6, dense ? 16 : 20),
           child: Row(children: [
-            const PangolinMark(size: 28),
-            const SizedBox(width: 9),
+            PangolinMark(size: dense ? 28 : 30),
+            SizedBox(width: dense ? 9 : 10),
             Column(crossAxisAlignment: CrossAxisAlignment.start, mainAxisSize: MainAxisSize.min, children: [
               Text(t.brand,
-                  style: PangolinText.h3.copyWith(color: c.fg1, fontWeight: FontWeight.w700, fontSize: 16, height: 1)),
+                  style: PangolinText.h3.copyWith(
+                      color: c.fg1, fontWeight: FontWeight.w700, fontSize: dense ? 16 : 17, height: 1)),
               const SizedBox(height: 3),
               Text('PANGOLIN',
                   style: PangolinText.caption.copyWith(
@@ -53,11 +57,12 @@ class NavSidebar extends ConsumerWidget {
         // Nav 列表
         for (final item in items)
           Padding(
-            padding: const EdgeInsets.only(bottom: 3),
+            padding: EdgeInsets.only(bottom: dense ? 3 : 4),
             child: _NavItem(
               icon: item.icon,
               label: item.label,
               active: current == item.view,
+              dense: dense,
               onTap: () => ref.read(navViewProvider.notifier).state = item.view,
             ),
           ),
@@ -69,11 +74,12 @@ class NavSidebar extends ConsumerWidget {
 }
 
 class _NavItem extends StatelessWidget {
-  const _NavItem({required this.icon, required this.label, required this.active, required this.onTap});
+  const _NavItem({required this.icon, required this.label, required this.active, required this.onTap, this.dense = true});
   final IconData icon;
   final String label;
   final bool active;
   final VoidCallback onTap;
+  final bool dense;
 
   @override
   Widget build(BuildContext context) {
@@ -84,17 +90,20 @@ class _NavItem extends StatelessWidget {
       clipBehavior: Clip.antiAlias,
       child: InkWell(
         onTap: onTap,
-        child: Padding(
-          padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 9),
-          child: Row(children: [
-            Icon(icon, size: 18, color: active ? c.accent : c.fg3),
-            const SizedBox(width: 11),
-            Text(label,
-                style: PangolinText.sm.copyWith(
-                    color: active ? c.accent : c.fg2,
-                    fontSize: 13.5,
-                    fontWeight: active ? FontWeight.w600 : FontWeight.w500)),
-          ]),
+        child: ConstrainedBox(
+          constraints: BoxConstraints(minHeight: dense ? 0 : 48),
+          child: Padding(
+            padding: EdgeInsets.symmetric(horizontal: dense ? 12 : 14, vertical: dense ? 9 : 13),
+            child: Row(children: [
+              Icon(icon, size: dense ? 18 : 20, color: active ? c.accent : c.fg3),
+              SizedBox(width: dense ? 11 : 12),
+              Text(label,
+                  style: PangolinText.sm.copyWith(
+                      color: active ? c.accent : c.fg2,
+                      fontSize: dense ? 13.5 : 15,
+                      fontWeight: active ? (dense ? FontWeight.w600 : FontWeight.w700) : FontWeight.w500)),
+            ]),
+          ),
         ),
       ),
     );