Every time in UTC, and every day as YYYY-MM-DD (closes #313)

AbuseIPDB's daily count keeps its day as a civil.Date, taken from the UTC
clock and written to reputation.json as "YYYY-MM-DD"; it was a time.Time
at midnight. A test runs sww discriminator with TZ 14 hours ahead of UTC
and checks the process line, the request line and clients.json are in
UTC. SPEC.md states the rule near its start; AGENTS.md makes it an iron
rule.

Model: opus-5-5

go.mod

@@ -3,6 +3,7 @@ module sneak.berlin/go/smallwebwaf
 go 1.26.0
 
 require (
+	cloud.google.com/go v0.123.0
 	github.com/corazawaf/coraza-coreruleset/v4 v4.25.0
 	github.com/corazawaf/coraza/v3 v3.8.2-0.20261022102553-d028be399c68
 	github.com/fsnotify/fsnotify v1.10.1