fix(keycloak): disable SSL requirement for master realm after start

Keycloak 26+ enforces SSL by default even for localhost, causing client
connections over plain HTTP to fail. Disable it via kcadm.sh post-start.
Also add user_realm_name to get_client() kwargs to fix authentication
against the master realm.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 2 people