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/history_test.go

@@ -31,9 +31,9 @@ func TestHistoryKeepsEachRequestOfTheClient(t *testing.T) {
 	s.get(fromDE, http.StatusOK, requestlog.ActionForward)
 	clk.advance(time.Second)
 	s.get(fromDE, http.StatusOK, requestlog.ActionForward)
-	s.get(fromDE, http.StatusForbidden, requestlog.ActionRateLimited)
+	s.get(fromDE, http.StatusForbidden, requestlog.ActionClientIsRateLimited)
 	clk.advance(time.Second)
-	s.get(fromDE, http.StatusForbidden, requestlog.ActionBanned)
+	s.get(fromDE, http.StatusForbidden, requestlog.ActionTemporarilyBanned)
 
 	want := ratelimit.History{
 		FirstSeen: start,