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/metrics_test.go

@@ -125,15 +125,15 @@ func TestMetricsCountLimitsAndBans(t *testing.T) {
 	})
 
 	// SWW_BAN_RESPONSE=close sends no status at all.
-	s.get(denied, 0, requestlog.ActionDenied)
+	s.get(denied, 0, requestlog.ActionClientDenied)
 
 	// A first broken limit bans for an hour.
 	s.get(client, http.StatusOK, requestlog.ActionForward)
-	s.get(client, 0, requestlog.ActionRateLimited)
+	s.get(client, 0, requestlog.ActionClientIsRateLimited)
 
 	metrics := s.scrape()
 	wantMetric(t, metrics,
-		`sww_requests_total{action="denied",instance="app",status_class="none"}`, 1)
+		`sww_requests_total{action="client_denied",instance="app",status_class="none"}`, 1)
 	wantMetric(t, metrics, `sww_rate_limit_hits_total{instance="app",`+
 		`kind="requests",window="minute"}`, 1)
 	wantMetric(t, metrics, `sww_offences_total{instance="app",kind="limit"}`, 1)
@@ -147,7 +147,7 @@ func TestMetricsCountLimitsAndBans(t *testing.T) {
 	// A limit broken again right after would ban for three hours, longer
 	// than SWW_MAX_BAN_DURATION, so the ban is permanent.
 	s.get(client, http.StatusOK, requestlog.ActionForward)
-	s.get(client, 0, requestlog.ActionRateLimited)
+	s.get(client, 0, requestlog.ActionClientIsRateLimited)
 
 	metrics = s.scrape()
 	wantMetric(t, metrics, `sww_rate_limit_hits_total{instance="app",`+