Tests, written before the change, for the check of PIXA_ names at startup: a PIXA_ variable that is not a setting's variable aborts naming it, PIXA_PORT aborts with a message saying to use PORT, and PIXA_CONFIG_PATH and every setting's variable are accepted. They call validateKnownEnvVars, which the change adds, so the package does not build until it lands. Model: opus-5-5