ClickHouse default user had no password, causing auth failures on recent
CH versions. Set password via from_env in clickhouse-users.xml, pass
credentials in JDBC URLs to SaaS services and tenant server containers.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
The default ClickHouse image restricts the 'default' user to localhost
only. Override with clickhouse-users.xml to allow connections from any
IP (needed for inter-container communication on the Docker network).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>