Caddy serves port 8080 in the Keycloak image. Keycloak listens on
127.0.0.1:8081 only. KEYCLOAK_ADMIN_IP_ALLOWLIST restricts /admin/* and
/realms/master/*. KEYCLOAK_TRUSTED_PROXIES sets the client IP from
X-Forwarded-For, as in the frontend image. The default allows all.
The build options are ENV in the runtime stage, so a start without
--optimized keeps them. The HEALTHCHECK probes Caddy and the management
port and follows PORT and KC_HTTP_MANAGEMENT_PORT.
Add bin/smoke-test-keycloak and the make target test-keycloak-image.
Remove the Scalingo buildpack for Keycloak.