Get In Flight Turn

GET 
/api/websites/:site_id/builder/turn/in-flight

Return the most recent in_flight turn id for the site, or 204.

The frontend calls this on mount: a positive answer triggers an immediate subscribe to the stream endpoint, and the chat UI fills in with replayed events while continuing live. A negative answer means "no turn to reattach — fall back to the persisted conversation (existing behaviour)."

Gated on WEBSITE_BUILDER_STREAM_REATTACH so the frontend's probe is a clean 404 when the feature is off — no need for the frontend to branch on a separate flag.

Request​