Preserve subscription-auth failures instead of rewriting them as missing API keys, and point Claude/Codex subscription users at the correct login and provider commands.
Fixes#254
Adapted to main's _resolve_api_client_from_settings() architecture.
Added _safe_resolve_auth() wrapper that catches ValueError and prints
a clear message before SystemExit(1).
Co-authored-by: José Maia <glitch-ux@users.noreply.github.com>