Outbound calls to 3rd-party services (threat-intel providers, future TI
lookups) MUST NOT advertise 'DECNET' in their user-agent — operators
running honeypots want their reconnaissance dependencies to look like
generic infra. New decnet.net.http.stealth_client() returns a fresh
httpx.AsyncClient with a curl-shaped UA (pinned to a single constant so
future siblings — browser-shaped, Go-shaped — sit next to it cleanly).
Internal egress (webhook → operator's own SIEM, swarm worker → master)
keeps its DECNET-tagged UA; the docstring is explicit about not routing
those through this client.