feat(client): 通用自适应弹出菜单(按屏幕位置上/下弹,不挡触发器)

新增 AdaptiveMenuButton:GlobalKey 量触发器矩形,据上下剩余空间决定向下/向上
弹出、右对齐裁剪到屏内,Overlay 全屏 barrier + 淡入缩放动画。「我的设备」⋯
菜单由 PopupMenuButton 换成它(重命名 + 强制退出/清除),修正小屏被遮挡问题。
devices_screen_test 同步改用 AdaptiveMenuButton 触发器断言。

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

client/lib/widgets/account_screens.dart

@@ -9,6 +9,7 @@ import '../l10n/app_text.dart';
 import '../models/device.dart';
 import '../pangolin_theme.dart';
 import '../services/device_identity.dart';
+import 'adaptive_menu.dart';
 import '../services/auth_api.dart';
 import '../state/account_providers.dart';
 import 'pangolin_button.dart';
@@ -215,50 +216,45 @@ class DevicesScreen extends ConsumerWidget {
   }
 
   // 本机:只给「重命名」(自我踢下线/清除没意义);其他设备:重命名+强制退出+清除。
-  Widget _menu(BuildContext context, WidgetRef ref, PangolinScheme c, Device d, bool isLocal) => PopupMenuButton<String>(
-        icon: Icon(PangolinIcons.moreVertical, size: 18, color: c.fg3),
-        color: c.surface,
-        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(PangolinRadius.md), side: BorderSide(color: c.border)),
-        itemBuilder: (_) => [
-          PopupMenuItem(value: 'rename', child: Row(children: [
-            Icon(PangolinIcons.edit, size: 16, color: c.fg2), const SizedBox(width: 10),
-            Text(t.devRename, style: PangolinText.sm.copyWith(color: c.fg1)),
-          ])),
-          if (!isLocal) ...[
-            PopupMenuItem(value: 'logout', child: Row(children: [
-              Icon(PangolinIcons.logOut, size: 16, color: c.fg2), const SizedBox(width: 10),
-              Text(t.devForceLogout, style: PangolinText.sm.copyWith(color: c.fg1)),
-            ])),
-            PopupMenuItem(value: 'clear', child: Row(children: [
-              Icon(PangolinIcons.trash, size: 16, color: c.danger), const SizedBox(width: 10),
-              Text(t.devClearLogin, style: PangolinText.sm.copyWith(color: c.danger)),
-            ])),
-          ],
-        ],
-        onSelected: (v) async {
-          if (v == 'rename') {
+  // 用 AdaptiveMenuButton:菜单按屏幕位置自动上/下弹、不遮挡 ⋯ 按钮。
+  Widget _menu(BuildContext context, WidgetRef ref, PangolinScheme c, Device d, bool isLocal) {
+    Future<void> confirmAction({required bool isClear}) async {
+      final label = isClear ? t.devClearLogin : t.devForceLogout;
+      final shown = d.name.isNotEmpty ? d.name : d.platformKind.label;
+      final ok = await _confirm(context, c,
+          title: '$label「$shown」',
+          body: isClear ? t.devClearLoginConfirm : t.devForceLogoutConfirm,
+          action: label);
+      if (!ok) return;
+      final n = ref.read(devicesProvider.notifier);
+      if (isClear) {
+        await n.remove(d.uuid);
+      } else {
+        await n.forceLogout(d.uuid);
+      }
+    }
+
+    return AdaptiveMenuButton(
+      icon: PangolinIcons.moreVertical,
+      iconColor: c.fg3,
+      items: [
+        AdaptiveMenuItem(
+          icon: PangolinIcons.edit,
+          label: t.devRename,
+          onSelected: () async {
             final newName = await _renameDialog(context, c, d);
             if (newName != null && newName.trim().isNotEmpty) {
               await ref.read(devicesProvider.notifier).rename(d.uuid, newName.trim());
             }
-            return;
-          }
-          final isClear = v == 'clear';
-          final label = isClear ? t.devClearLogin : t.devForceLogout;
-          final shown = d.name.isNotEmpty ? d.name : d.platformKind.label;
-          final ok = await _confirm(context, c,
-              title: '$label「$shown」',
-              body: isClear ? t.devClearLoginConfirm : t.devForceLogoutConfirm,
-              action: label);
-          if (!ok) return;
-          final n = ref.read(devicesProvider.notifier);
-          if (isClear) {
-            await n.remove(d.uuid);
-          } else {
-            await n.forceLogout(d.uuid);
-          }
-        },
-      );
+          },
+        ),
+        if (!isLocal) ...[
+          AdaptiveMenuItem(icon: PangolinIcons.logOut, label: t.devForceLogout, onSelected: () => confirmAction(isClear: false)),
+          AdaptiveMenuItem(icon: PangolinIcons.trash, label: t.devClearLogin, danger: true, onSelected: () => confirmAction(isClear: true)),
+        ],
+      ],
+    );
+  }
 
   // 危险操作二次确认弹窗(走 token 配色)。
   Future<bool> _confirm(BuildContext context, PangolinScheme c,