fix: add ClickHouse password authentication

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>

docker/clickhouse-users.xml

@@ -1,6 +1,7 @@
 <clickhouse>
   <users>
     <default>
+      <password from_env="CLICKHOUSE_PASSWORD" />
       <networks>
         <ip>::/0</ip>
       </networks>