CRITICAL: Config validation no longer kills entire process when one service has invalid config (missing compose file, etc.)

Invalid services are now logged as warnings and skipped, allowing valid services to continue monitoring

/health endpoint now exposes config_warnings array listing any services that failed validation

Config validation behavior: service-level errors (missing files, invalid paths) are non-fatal and collected in InvalidServices

Only global validation errors (invalid runtime) remain fatal

Startup logs now show clear warnings for each skipped service with reason