Add link-column CRUD APIs to the HTML Page SDK

[renjie-run]

Summary

• Add single-link and batch link add/delete methods to the low-level HTML Page API.
• Expose addLink, deleteLink, batchAddLinks, and batchDeleteLinks through the public SDK.
• Forward preview table configuration for AI agent previews.
• Document single-row and row-oriented batch link usage in the README.

Testing

• Added unit coverage for API request payloads, delete requests, batch operations, preview configuration, and SDK delegation.

[seafile-dev]

已核对 SDK 的请求路径、camelCase 到 snake_case 的参数转换、AI 预览权限转发及 Jest 覆盖；与服务端新增接口和设计文档一致。