- source build.func (script was unrunnable without it)
- validate DB_NAME/DB_USER/DB_PORT/NEXUS_APP_IP before SQL/pg_hba use
- rotate password when role exists but credentials file is missing
webapp-pattern ct/install pair: PGDG repo, database nexus with
least-privilege owner role, pg_hba allowlist restricted to the nexus
app LXC (explicit reject for everything else), pgvector created by the
installer, credentials/DSN summary in /root/nexus-db.credentials.
Idempotent re-runs keep role/db and do not rotate the password.
l.kirchner