FIX: Support onebox cache invalidation in chat messages

FIX: Support onebox cache invalidation in chat messages: a task in bird-critic-1.5-full-300 (Harbor dataset). Chat messages can contain oneboxes (embedded previews of URLs), which are cached for performance. When the content at a URL changes or needs to be refreshed, the system must provide a way…

The task

Chat messages can contain oneboxes (embedded previews of URLs), which are cached for performance. When the content at a URL changes or needs to be refreshed, the system must provide a way to bypass the cache and fetch fresh content.

Part of kochsnow/bird-critic-1.5-full-300.