Pydantic AI Web chat UI (`Agent.to_web()`, `clai web`): the local chat endpoint does not validate the `Host` header

Summary The Pydantic AI development web chat UI Agent.toweb, clai web does not validate the Host header of incoming requests. A website a developer visits can use DNS rebinding to make requests to a chat UI running on that developer's machine appear same-origin to the browser, causing the served...