Rate assistant responses with a thumbs up or down

Every assistant message (on an agent's public link, in the playground, and in a saved conversation's transcript) now has a thumbs-up and thumbs-down control.

Clicking either opens a short dialog instead of submitting right away. A thumbs-down lets you optionally pick an issue category (UI bug, didn't understand the request, refused to help without good reason, incorrect product information, incomplete response, irrelevant recommendation, should have searched the catalog, problem with cart or checkout, inappropriate tone, or other) and add a free-text comment; a thumbs-up only offers the comment. Cancel discards the dialog, Submit saves the rating.

A rating belongs to the message, not the surface it was given on: rate one live on the public link or in the playground, and it shows up the same way later when that conversation is reopened in the dashboard. Rating an already-rated message again reopens the dialog pre-filled with what was submitted, so submitting revises it.

Reviewing a saved conversation in the dashboard also shows a persistent block under any rated message with its category and/or comment, so you don't have to reopen the dialog to see what was said. That block is dashboard-only: live in the playground or on the public link, a rating shows only as the highlighted thumb, since you just filled in the dialog yourself.

On the public link, submitting also shows shoppers a one-line notice that their feedback and the conversation may be reviewed internally.