fix(client): 账号菜单弹按钮正上方不遮挡 + side-user hover 变色

对照原型修两点：
1. 菜单原先 over 盖住 side-user 按钮；改为按「菜单估高」把菜单完整弹到按钮上方
   留 8px 间隙，触发器始终可见（对齐原型）
2. side-user 抽成 _SideUserTile，加 hover 变色（t.sideHover，与左侧 nav 一致）
- user_menu_width_test 增断言：菜单末项底 ≤ 触发器顶（不遮挡）

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TSKEiHsvauyxYUW2itzUXX

client/lib/screens/shell/app_shell.dart

@@ -84,30 +84,38 @@ class _AppShellState extends ConsumerState<AppShell> {
   bool _forceDialogShown = false;
   bool _licenseDialogShown = false;
   final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();
-  // 侧栏底部用户区，用于实测宽度让弹出菜单等宽 + 定位（向上弹，不溢出内容区）
-  final GlobalKey _sideUserKey = GlobalKey();
 
-  /// 打开账号菜单（个人设置 / 退出登录）。菜单宽度 = 用户区实测宽度（自动与侧栏
-  /// 内容等宽、绝不溢出到内容区）；底部空间不足时 showMenu 自动向上弹。
-  void _openUserMenu(BuildContext context) {
-    final t = context.tokens;
-    final rb = _sideUserKey.currentContext?.findRenderObject() as RenderBox?;
+  /// 打开账号菜单（个人设置 / 退出登录）。[anchorContext] = 用户区组件的 context，
+  /// 据其实测宽度让菜单等宽（不溢出内容区）、据其位置把菜单**完整弹到按钮正上方**
+  /// （留 8px 间隙，不遮挡触发器，对齐原型）。
+  void _openUserMenu(BuildContext anchorContext) {
+    final t = anchorContext.tokens;
+    final rb = anchorContext.findRenderObject() as RenderBox?;
     final overlay =
-        Overlay.of(context).context.findRenderObject() as RenderBox?;
+        Overlay.of(anchorContext).context.findRenderObject() as RenderBox?;
     if (rb == null || overlay == null) return;
     final topLeft = rb.localToGlobal(Offset.zero, ancestor: overlay);
-    final rect = topLeft & rb.size;
+    final items = <PopupMenuEntry<String>>[
+      _userMenuItem('profile', Icons.manage_accounts_outlined, '个人设置', t),
+      _userMenuItem('logout', Icons.logout, '退出登录', t),
+    ];
+    // 菜单弹到按钮上方：top = 按钮顶 − 菜单估高 − 间隙（菜单项 40 + 上下 padding 8*2）
+    const itemH = 40.0;
+    final menuH = items.length * itemH + 16;
+    final top = topLeft.dy - menuH - 8;
     showMenu<String>(
-      context: context,
-      position: RelativeRect.fromRect(rect, Offset.zero & overlay.size),
+      context: anchorContext,
+      position: RelativeRect.fromLTRB(
+        topLeft.dx,
+        top,
+        overlay.size.width - topLeft.dx - rb.size.width,
+        overlay.size.height - top,
+      ),
       constraints: BoxConstraints.tightFor(width: rb.size.width),
       color: t.menuUserBg,
       elevation: 8,
       shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(6)),
-      items: [
-        _userMenuItem('profile', Icons.manage_accounts_outlined, '个人设置', t),
-        _userMenuItem('logout', Icons.logout, '退出登录', t),
-      ],
+      items: items,
     ).then((v) {
       if (v == 'logout') _logout();
     });
@@ -302,8 +310,6 @@ class _AppShellState extends ConsumerState<AppShell> {
 
   Widget _buildSideUser(BuildContext context, AuthUser user) {
     final t = context.tokens;
-    final initial = (user.realName.isNotEmpty ? user.realName : user.username);
-    final pic = initial.isNotEmpty ? initial.characters.first : '用';
     final shopName = ref.watch(shopInfoProvider).valueOrNull?.name ?? user.shopNo;
     return Column(
       children: [
@@ -314,59 +320,11 @@ class _AppShellState extends ConsumerState<AppShell> {
         ),
         Padding(
           padding: const EdgeInsets.only(bottom: 8),
-          child: GestureDetector(
-            behavior: HitTestBehavior.opaque,
-            onTap: () => _openUserMenu(context),
-            child: Container(
-              key: _sideUserKey,
-              padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 9),
-              decoration: BoxDecoration(
-                borderRadius: BorderRadius.circular(6),
-              ),
-              child: Row(
-                children: [
-                  Container(
-                    width: 34,
-                    height: 34,
-                    decoration: BoxDecoration(
-                      color: t.sideActiveBg,
-                      shape: BoxShape.circle,
-                    ),
-                    alignment: Alignment.center,
-                    child: Text(pic,
-                        style: TextStyle(
-                            color: t.sideActiveFg,
-                            fontWeight: FontWeight.w700,
-                            fontSize: 14)),
-                  ),
-                  const SizedBox(width: 10),
-                  Expanded(
-                    child: Column(
-                      crossAxisAlignment: CrossAxisAlignment.start,
-                      mainAxisSize: MainAxisSize.min,
-                      children: [
-                        Text(
-                          user.realName.isNotEmpty
-                              ? user.realName
-                              : user.username,
-                          style: TextStyle(
-                              color: t.sideActiveFg,
-                              fontSize: 13,
-                              fontWeight: FontWeight.w600),
-                          overflow: TextOverflow.ellipsis,
-                        ),
-                        Text(
-                          '$shopName · ${_roleLabel(user.role)}',
-                          style: TextStyle(color: t.sideMuted, fontSize: 11),
-                          overflow: TextOverflow.ellipsis,
-                        ),
-                      ],
-                    ),
-                  ),
-                  Icon(Icons.keyboard_arrow_down, size: 14, color: t.sideMuted),
-                ],
-              ),
-            ),
+          child: _SideUserTile(
+            user: user,
+            shopName: shopName,
+            roleLabel: _roleLabel(user.role),
+            onTap: _openUserMenu,
           ),
         ),
       ],
@@ -788,6 +746,92 @@ class _ShopMark extends StatelessWidget {
   }
 }
 
+// ── 侧栏底部用户区（原型 .side-user）：hover 变色（同 nav 的 side-hover），点开账号菜单 ──
+class _SideUserTile extends StatefulWidget {
+  final AuthUser user;
+  final String shopName;
+  final String roleLabel;
+  final void Function(BuildContext anchorContext) onTap;
+  const _SideUserTile({
+    required this.user,
+    required this.shopName,
+    required this.roleLabel,
+    required this.onTap,
+  });
+
+  @override
+  State<_SideUserTile> createState() => _SideUserTileState();
+}
+
+class _SideUserTileState extends State<_SideUserTile> {
+  bool _hover = false;
+
+  @override
+  Widget build(BuildContext context) {
+    final t = context.tokens;
+    final u = widget.user;
+    final initial = u.realName.isNotEmpty ? u.realName : u.username;
+    final pic = initial.isNotEmpty ? initial.characters.first : '用';
+    return MouseRegion(
+      cursor: SystemMouseCursors.click,
+      onEnter: (_) => setState(() => _hover = true),
+      onExit: (_) => setState(() => _hover = false),
+      child: GestureDetector(
+        behavior: HitTestBehavior.opaque,
+        onTap: () => widget.onTap(context),
+        child: Container(
+          padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 9),
+          decoration: BoxDecoration(
+            color: _hover ? t.sideHover : Colors.transparent,
+            borderRadius: BorderRadius.circular(6),
+          ),
+          child: Row(
+            children: [
+              Container(
+                width: 34,
+                height: 34,
+                decoration: BoxDecoration(
+                  color: t.sideActiveBg,
+                  shape: BoxShape.circle,
+                ),
+                alignment: Alignment.center,
+                child: Text(pic,
+                    style: TextStyle(
+                        color: t.sideActiveFg,
+                        fontWeight: FontWeight.w700,
+                        fontSize: 14)),
+              ),
+              const SizedBox(width: 10),
+              Expanded(
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  mainAxisSize: MainAxisSize.min,
+                  children: [
+                    Text(
+                      u.realName.isNotEmpty ? u.realName : u.username,
+                      style: TextStyle(
+                          color: t.sideActiveFg,
+                          fontSize: 13,
+                          fontWeight: FontWeight.w600),
+                      overflow: TextOverflow.ellipsis,
+                    ),
+                    Text(
+                      '${widget.shopName} · ${widget.roleLabel}',
+                      style: TextStyle(color: t.sideMuted, fontSize: 11),
+                      overflow: TextOverflow.ellipsis,
+                    ),
+                  ],
+                ),
+              ),
+              Icon(Icons.keyboard_arrow_down, size: 14, color: t.sideMuted),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}
+
 // ── 侧栏导航项（原型 .nav, 40h）───────────────────────────────────────────────
 class _SidebarNav extends StatefulWidget {
   final _NavItem item;

client/test/user_menu_width_test.dart

@@ -103,5 +103,12 @@ void main() {
         reason: '菜单应与触发器等宽(~194)，不应外扩到 218 而溢出');
     expect(itemRect.right, lessThanOrEqualTo(219),
         reason: '菜单右缘不得越过侧栏右缘(218)盖住内容区');
+
+    // 菜单整体在触发器上方，不遮挡 side-user 按钮（菜单末项底 ≤ 触发器文本顶）
+    final menuBottom =
+        tester.getRect(find.byType(PopupMenuItem<String>).last).bottom;
+    final triggerTop = tester.getRect(find.textContaining('管理员')).top;
+    expect(menuBottom, lessThanOrEqualTo(triggerTop),
+        reason: '菜单应弹在按钮上方，不得盖住 side-user 触发器');
   });
 }