CrowdSec decision list fetched, kept, and its clients banned until the decision ends (closes #106)

SWWAF_CROWDSEC_LAPI_URL and SWWAF_CROWDSEC_LAPI_KEY name an engine whose
decision list, <url>/v1/decisions, is fetched every minute with the key in
X-Api-Key and kept as a blocklist is: used while a fetch fails, and across
restarts through reputation.json. Ban decisions on an Ip or a Range end at
the fetch time plus their duration. A listed client's request is refused and
bans its netblock with the cause crowdsec until the decision ends; bans.json,
ban notes and metrics take the cause.

Judgement call: fetched every minute, not a setting.
Judgement call: a crowdsec ban never lengthens a limit ban.
Judgement call: a lifted crowdsec ban is remade while its decision lasts.

Model: opus-5-5

internal/alerts/alerts.go

@@ -46,8 +46,9 @@ const (
 	EventAnomaly = "anomaly"
 	// EventWAFBlock comes with the Core Rule Set; nothing raises it yet.
 	EventWAFBlock = "waf_block"
-	// EventReputationHit is a request whose client a blocklist or a DNSBL
-	// zone lists, or whose AbuseIPDB score is a hit.
+	// EventReputationHit is a request whose client a blocklist, the
+	// CrowdSec decision list or a DNSBL zone lists, or whose AbuseIPDB score
+	// is a hit.
 	EventReputationHit = "reputation_hit"
 	// EventSourceFailure is GeoJS failing or refusing smallwebwaf, a fetch
 	// of a list failing, a query to a DNSBL zone or a check with AbuseIPDB