feat: 更新学生余额页面的分页设置，增加页面大小选择功能

apps/admin/src/pages/Wallets/index.tsx

@@ -273,7 +273,12 @@ const WalletsPage: React.FC = () => {
         dataSource={rows}
         columns={columns}
         rowSelection={{ selectedRowKeys, onChange: setSelectedRowKeys }}
-        pagination={{ pageSize: 15, showTotal: (total) => `共 ${total} 人` }}
+        pagination={{
+          defaultPageSize: 15,
+          showSizeChanger: true,
+          pageSizeOptions: [15, 30, 50, 100],
+          showTotal: (total) => `共 ${total} 人`,
+        }}
       />
       <Modal
         title={`${selected?.studentName || ''} - 余额操作`}