Four concrete IntelProvider impls — three per-IP queries plus one bulk
feed:
* GreyNoiseProvider — community endpoint, optional API key for higher
rate limit. 404 = unknown (cache the absence so we don't re-query).
* AbuseIPDBProvider — score threshold mapping (>=75 malicious, >=25
suspicious, else benign). Self-disables with a clear error when no
API key is configured rather than burning quota.
* FeodoProvider — fetches the bulk botnet C2 IP feed once per refresh
window and answers every lookup from an in-memory set. Listed = C2.
* ThreatFoxProvider — POST /api/v1/ search_ioc query, optional Auth-Key
header. Match in data[] = malicious; no_result = absence-not-benign.
Every provider routes through decnet.net.http.stealth_client so the
egress UA never leaks 'DECNET'.
