refactor(client): SubScaffold 六合一(视觉零变化)+ tablet 注释订正 + 平板通知铃入口(#20)

client/lib/widgets/account_screens.dart

@@ -20,39 +20,7 @@ import '../services/auth_api.dart';
 import '../state/account_providers.dart';
 import 'pangolin_button.dart';
 import 'pangolin_icons.dart';
-
-/// 通用:带返回箭头的子页骨架。embedded=true 时只返回内容（desktop 内容区下钻，
-/// 返回/标题由外层 shell 顶栏提供），否则整页 Scaffold（mobile/tablet 全屏 push）。
-class _SubScaffold extends StatelessWidget {
-  const _SubScaffold({required this.title, required this.child, this.onBack, this.embedded = false});
-  final String title;
-  final Widget child;
-  final VoidCallback? onBack;
-  final bool embedded;
-  @override
-  Widget build(BuildContext context) {
-    final c = context.pangolin;
-    if (embedded) return child;
-    return Scaffold(
-      backgroundColor: c.bg,
-      body: SafeArea(
-        child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
-          Padding(
-            padding: const EdgeInsets.fromLTRB(8, 6, 16, 10),
-            child: Row(children: [
-              IconButton(
-                onPressed: onBack ?? () => Navigator.of(context).maybePop(),
-                icon: Icon(PangolinIcons.arrowLeft, size: 22, color: c.fg1),
-              ),
-              Text(title, style: PangolinText.h3.copyWith(color: c.fg1, fontWeight: FontWeight.w700)),
-            ]),
-          ),
-          Expanded(child: child),
-        ]),
-      ),
-    );
-  }
-}
+import 'sub_scaffold.dart';
 
 /// ── 设置(移动端从「我的」下钻)── 复用桌面 SettingsPage 内容,套移动返回栏。
 class SettingsScreen extends StatelessWidget {
@@ -62,7 +30,7 @@ class SettingsScreen extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return _SubScaffold(title: t.settingsTitle, onBack: onBack, child: const SettingsPage());
+    return SubScaffold(title: t.settingsTitle, onBack: onBack, child: const SettingsPage());
   }
 }
 
@@ -113,7 +81,7 @@ class DevicesScreen extends ConsumerWidget {
           ]),
         );
 
-    return _SubScaffold(
+    return SubScaffold(
         title: t.myDevices, onBack: onBack, embedded: embedded, child: _DevicesAutoRefresh(child: content()));
   }
 
@@ -314,7 +282,7 @@ class _RedeemScreenState extends ConsumerState<RedeemScreen> {
   Widget build(BuildContext context) {
     final c = context.pangolin;
     final t = widget.t;
-    return _SubScaffold(
+    return SubScaffold(
       title: t.redeemTitle,
       onBack: widget.onBack,
       embedded: widget.embedded,
@@ -379,7 +347,7 @@ class ContactScreen extends StatelessWidget {
               accent: ch.accent,
             ))
         .toList();
-    return _SubScaffold(
+    return SubScaffold(
       title: t.contactTitle,
       onBack: onBack,
       child: ListView(padding: const EdgeInsets.fromLTRB(20, 4, 20, 24), children: [

client/lib/widgets/sub_scaffold.dart

@@ -0,0 +1,57 @@
+// sub_scaffold.dart — 通用「返回箭头 + 标题」子页脚手架(六处收敛,视觉零变化)。
+//
+// 收敛自 account_screens.dart/orders_page.dart 的私有 `_SubScaffold`,以及
+// purchase_page.dart/payment_page.dart/invite_page.dart/notifications_page.dart
+// 里结构相同的内联等价实现。逐像素沿用原实现(同 padding/字号/图标),纯收敛非重设计。
+//
+// embedded=true 时只返回内容(desktop 内容区下钻,返回/标题由外层 shell 顶栏提供);
+// 否则整页 Scaffold + SafeArea + 返回箭头行(mobile/tablet 全屏 push)。
+// wrapPageBody=true 时由本组件把 child 套进 PageBody(桌面内容页统一宽度容器);默认
+// false——调用方若已自行用 PageBody 包裹 child(如购买页需要 wide 变体),避免重复包裹。
+import 'package:flutter/material.dart';
+
+import '../pangolin_theme.dart';
+import 'page_body.dart';
+import 'pangolin_icons.dart';
+
+class SubScaffold extends StatelessWidget {
+  const SubScaffold({
+    super.key,
+    required this.title,
+    required this.child,
+    this.onBack,
+    this.embedded = false,
+    this.wrapPageBody = false,
+  });
+
+  final String title;
+  final Widget child;
+  final VoidCallback? onBack;
+  final bool embedded;
+  final bool wrapPageBody;
+
+  @override
+  Widget build(BuildContext context) {
+    final c = context.pangolin;
+    final body = wrapPageBody ? PageBody(child: child) : child;
+    if (embedded) return body;
+    return Scaffold(
+      backgroundColor: c.bg,
+      body: SafeArea(
+        child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
+          Padding(
+            padding: const EdgeInsets.fromLTRB(8, 6, 16, 10),
+            child: Row(children: [
+              IconButton(
+                onPressed: onBack ?? () => Navigator.of(context).maybePop(),
+                icon: Icon(PangolinIcons.arrowLeft, size: 22, color: c.fg1),
+              ),
+              Text(title, style: PangolinText.h3.copyWith(color: c.fg1, fontWeight: FontWeight.w700)),
+            ]),
+          ),
+          Expanded(child: body),
+        ]),
+      ),
+    );
+  }
+}