Name request log actions so they say what they mean (closes #229)

Rename too_large, rate_limited, rule_blocked and denied, and split banned
into temporarily_banned and permanently_banned by whether the ban runs out.
A request that makes a ban permanent gets permanently_banned. A ban the
request itself makes gets the value for that ban, and in observe mode
would_action names the ban enforce mode would have made.

The offence kind rule_blocked follows, as a metric label and a key in
clients.json.

Model: opus-5-5

internal/discriminator/ratelimits.go

@@ -42,7 +42,9 @@ func (rateLimits) check(_ context.Context, rq *request, now time.Time) *verdict
 
 	rq.banForLimit(now, hit, rq.h.config.BanResponse)
 
-	return &verdict{action: requestlog.ActionRateLimited, figures: limitFigures(hit)}
+	return &verdict{
+		action: requestlog.ActionClientIsRateLimited, figures: limitFigures(hit),
+	}
 }
 
 // overAWholeRateLimit reports whether the heuristic rate_limits will refuse the