Summary

• accept PEP 508 extras in SYSTEM INSTALL PYTHON PACKAGE, e.g. confluent-kafka[protobuf, avro]
• normalize the package lookup name for pip show and uninstall so extras-bearing specs do not break package management
• refresh Python import state after install by re-processing site directories and invalidating import caches
• extend __path__ only for legacy namespace packages declared via pkg_resources.declare_namespace() so packages like google.protobuf become visible after install without broadening ordinary package semantics
• warn when installing confluent-kafka because the wheel bundles its own librdkafka, which can conflict with Proton's in-process librdkafka; the warning points users to confluent-kafka==2.1.1 as a known-good version and suggests checking confluent_kafka.libversion() at runtime
• add focused unit coverage for extras parsing, lookup-name behavior, .pth processing, and namespace package refresh behavior