fix(lint): name the UserEventRetentionDays doc comment after its const

staticcheck ST1022: the comment led with "UserEventRetention", dropping the Days
suffix, so it didn't match the identifier it documents.

Author: AppsGanin

internal/model/events.go

@@ -91,6 +91,6 @@ func ValidUserEvent(k string) bool {
 	return false
 }
 
-// UserEventRetention is how long audit rows are kept before the retention sweep
+// UserEventRetentionDays is how long audit rows are kept before the retention sweep
 // drops them.
 const UserEventRetentionDays = 90