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/denynets.go

@@ -19,7 +19,7 @@ func (denyNets) check(_ context.Context, rq *request, _ time.Time) *verdict {
 	for _, netblock := range rq.h.config.DenyNets {
 		if netblock.Contains(rq.client) {
 			return &verdict{
-				action:  requestlog.ActionDenied,
+				action:  requestlog.ActionClientDenied,
 				figures: map[string]any{figureNetblock: netblock.String()},
 			}
 		}