feat(client): toast 限定主显示区/自适应宽/上限80%/超长多行居中(1.0.26)

按真相源新规:toast 改为自定义 Overlay 实现(widgets/pangolin_toast.dart),完全控制布局——
不覆盖左侧栏(left=侧栏宽 desktop204/tablet232/mobile0)、宽度自适应内容上限主区80%、超长文本
多行、主区内水平居中贴底、淡入轻起;仍走语义 token 明暗适配。自动连接改用 showPangolinToast。
同步 design/CONTRACT.md §2 toast 规格(canonical=showPangolinToast)。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/lib/main.dart

@@ -22,9 +22,7 @@ import 'system_tray.dart';
 import 'widgets/auth_screen.dart';
 import 'widgets/onboarding_screen.dart';
 import 'widgets/pangolin_logo.dart';
-
-/// 全局 ScaffoldMessenger key:供无 BuildContext 处(如自动连接)弹 SnackBar/toast。
-final rootMessengerKey = GlobalKey<ScaffoldMessengerState>();
+import 'widgets/pangolin_toast.dart';
 
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();
@@ -101,7 +99,6 @@ class _PangolinAppState extends ConsumerState<PangolinApp> {
     final mode = ref.watch(themeModeProvider);
     return MaterialApp(
       title: '穿山甲',
-      scaffoldMessengerKey: rootMessengerKey,
       debugShowCheckedModeBanner: false,
       theme: PangolinTheme.light,
       darkTheme: PangolinTheme.dark,
@@ -155,13 +152,9 @@ class _RootFlowState extends ConsumerState<RootFlow> {
       if (settings.autoConnect && phase == VpnPhase.off) {
         logLine('AutoConnect', 'triggering connect → ${node.code}');
         ref.read(connectionProvider.notifier).toggle();
-        // 自动连接 toast:告知用户「正在自动连接到 X」。
+        // 自动连接 toast:「正在自动连接到 X」(主显示区内居中,见 pangolin_toast)。
         final t = ref.read(appTextProvider);
-        rootMessengerKey.currentState?.showSnackBar(SnackBar(
-          content: Text(t.autoConnectingTo(node.localizedName(t.lang))),
-          behavior: SnackBarBehavior.floating,
-          duration: const Duration(seconds: 3),
-        ));
+        if (mounted) showPangolinToast(context, t.autoConnectingTo(node.localizedName(t.lang)));
       } else {
         logLine('AutoConnect', 'NOT connecting (autoConnect=${settings.autoConnect} phase=$phase)');
       }

client/lib/widgets/pangolin_toast.dart

@@ -0,0 +1,76 @@
+// pangolin_toast.dart — 统一轻提示(toast)。真相源规格见 design/CONTRACT.md §2「Toast/SnackBar」。
+//
+// 用 Overlay 实现(非 Material SnackBar),以完全控制布局:
+//   · 只在主显示区内(避开左侧栏:desktop 204 / tablet 232 / mobile 0)。
+//   · 宽度自适应内容,上限为主显示区的 80%;超长则文本多行、居中。
+//   · 跟随明暗主题:surface 底 + fg1 字 + border 描边 + md 圆角 + 柔和暖阴影,淡入轻起。
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+
+import '../core/responsive/form_factor.dart';
+import '../pangolin_theme.dart';
+
+/// 在主显示区底部居中弹一条 toast(默认 3 秒)。需要一个能拿到 Overlay/主题的 context。
+void showPangolinToast(BuildContext context, String message,
+    {Duration duration = const Duration(seconds: 3)}) {
+  final overlay = Overlay.maybeOf(context, rootOverlay: true);
+  if (overlay == null) return;
+  late final OverlayEntry entry;
+  entry = OverlayEntry(builder: (_) => _PangolinToast(message: message));
+  overlay.insert(entry);
+  Timer(duration, () {
+    if (entry.mounted) entry.remove();
+  });
+}
+
+class _PangolinToast extends StatelessWidget {
+  const _PangolinToast({required this.message});
+  final String message;
+
+  @override
+  Widget build(BuildContext context) {
+    final c = context.pangolin;
+    // 侧栏宽度(避开它):取自各 shell 的 NavSidebar 宽度。
+    final sidebar = switch (context.formFactor) {
+      FormFactor.desktop => 204.0,
+      FormFactor.tablet => 232.0,
+      FormFactor.mobile => 0.0,
+    };
+    final w = MediaQuery.sizeOf(context).width;
+    final contentW = (w - sidebar).clamp(0.0, w);
+    return Positioned(
+      left: sidebar,
+      right: 0,
+      bottom: 28,
+      child: IgnorePointer(
+        child: TweenAnimationBuilder<double>(
+          tween: Tween(begin: 0, end: 1),
+          duration: const Duration(milliseconds: 240),
+          curve: Curves.easeOut,
+          builder: (_, t, child) =>
+              Opacity(opacity: t, child: Transform.translate(offset: Offset(0, (1 - t) * 8), child: child)),
+          child: Center(
+            child: ConstrainedBox(
+              constraints: BoxConstraints(maxWidth: contentW * 0.8),
+              child: Container(
+                padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
+                decoration: BoxDecoration(
+                  color: c.surface,
+                  borderRadius: BorderRadius.circular(PangolinRadius.md),
+                  border: Border.all(color: c.border),
+                  boxShadow: PangolinShadow.sm,
+                ),
+                child: Text(
+                  message,
+                  textAlign: TextAlign.center,
+                  style: PangolinText.sm.copyWith(color: c.fg1, fontWeight: FontWeight.w600),
+                ),
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}

client/pubspec.yaml

@@ -1,7 +1,7 @@
 name: pangolin_vpn
 description: 穿山甲 · Pangolin — 极简、稳定、跨平台网络加速客户端。
 publish_to: "none"
-version: 1.0.25+26
+version: 1.0.26+27
 
 environment:
   sdk: ^3.5.0

client/windows/installer/pangolin.iss

@@ -3,7 +3,7 @@
 ; 前置: 先在 client/ 跑 `flutter build windows`(Release),产物在
 ;       ..\..\build\windows\x64\runner\Release
 #define MyAppName "穿山甲 Pangolin"
-#define MyAppVersion "1.0.25"
+#define MyAppVersion "1.0.26"
 #define MyAppPublisher "Pangolin"
 #define MyAppExeName "pangolin_vpn.exe"
 #define BuildDir "..\..\build\windows\x64\runner\Release"