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

The request log's `action` values now say what they mean, as sneak named them: `request_header_too_large`, `client_is_rate_limited`, `blocked_by_block_rule` and `client_denied`, with no aliases. `banned` splits into `temporarily_banned` and `permanently_banned`, by whether the ban runs out. When a permanent ban also covers a client, that ban is the one reported.

Trips a reader: a request over a rate limit stays `client_is_rate_limited` even when the ban it makes is permanent.
Disclosure: the offence key `rule_blocked` is renamed in `clients.json` too, so an existing file holding it stops the start and must be removed. Its `version` stays 1.

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