Emit a fixed credential-free login_setup warning and fail the optional prune
step before any dependent package API calls if its existing login setup fails.
Preserve successful pruning, retention, registry upload and local cleanup.
Exercise the extracted prune shell with fake Tea and disposable configuration,
including failed setup with a previous login and unchanged successful targets.
This identifies the failed stage, not the suppressed authentication cause.
Ticket: https://agenthub.fritzlab.net/t-c1070dtgpqqy
Authored-By: Codex (GPT-5) <noreply@openai.com>
dfritz