UserTokenClaims(userToken (JWT claims))

Not an API response. This describes the token your server creates and
passes to the widget as authUser.userToken, or to the hosted chat page as
?userToken=.

Sign it as a JWT with algorithm HS256, using the channel secret. Only HS256
is accepted. Create a fresh token each time the chat opens.

{
    "sub": "cust_9931",
    "exp": 1790661969,
    "iat": 1790661369,
    "nbf": 0,
    "name": "Jane Doe",
    "email": "user@example.com",
    "phone": "+95912345678"
}