The session transfer handler was blindly redirecting to the continue URL
from the signed token. Use saferedirect with a trust center domain check
to prevent open redirects, and only trigger session transfer for known
trust center custom domains instead of any non-base-URL host.
Signed-off-by: Bryan Frimin <bryan@getprobo.com>
After OIDC login, if the redirect targets a trust center custom
domain, the callback now redirects through a session-transfer
endpoint on that domain. The endpoint verifies an HMAC-signed,
time-limited token and sets the session cookie on the custom
domain before redirecting to the final URL.
The continue URL is bound into the signed token payload to
prevent open-redirect attacks via parameter tampering.
Signed-off-by: Bryan Frimin <bryan@getprobo.com>
