feat: persist system settings and refine admin layouts

frontend/src/pages/Users/Users.tsx

@@ -115,11 +115,17 @@ function Users() {
 
   return (
     <AppLayout>
-      <div style={{ marginBottom: 16, display: 'flex', justifyContent: 'space-between' }}>
-        <h2>用户管理</h2>
-        <Button type="primary" icon={<PlusOutlined />} onClick={handleAdd}>添加用户</Button>
+      <div className="page-shell">
+        <div className="page-shell__header">
+          <h2 style={{ margin: 0 }}>用户管理</h2>
+          <Button type="primary" icon={<PlusOutlined />} onClick={handleAdd}>添加用户</Button>
+        </div>
+        <div className="page-shell__body">
+          <div className="table-scroll-region" style={{ height: '100%' }}>
+            <Table columns={columns} dataSource={users} rowKey="id" loading={loading} scroll={{ x: 'max-content', y: 'calc(100% - 72px)' }} tableLayout="fixed" />
+          </div>
+        </div>
       </div>
-      <Table columns={columns} dataSource={users} rowKey="id" loading={loading} scroll={{ x: 'max-content' }} tableLayout="fixed" />
       <Modal
         title={editingUser ? '编辑用户' : '添加用户'}
         open={modalVisible}