Name log fields, metrics and the Core Rule Set package for what they are (closes #192)

The first half of the naming audit: names now say what they are. `internal/waf` is `internal/coreruleset`. Log fields, the action `blocked_by_core_rule_set`, the metric and the alert event say Core Rule Set. Timings end `_ms`. Percentages say of what, as `rate_limit_percent` and `bytes_limit_percent`. Setting names follow in #234.

Judgement call: `blocked_by_core_rule_set`, not the audit's `core_rule_set_blocked`, to match `blocked_by_block_rule`.
Trips a reader: an existing state file holding `waf_blocked` or the anomaly scope `watch` stops the start and must be removed. `SWW_ALERT_EVENTS` listing `waf_block` must list `core_rule_set_match`.

Model: opus-5-5

internal/discriminator/coreruleset.go

@@ -9,8 +9,8 @@ import (
 
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
 	"sneak.berlin/go/smallwebwaf/internal/config"
+	"sneak.berlin/go/smallwebwaf/internal/coreruleset"
 	"sneak.berlin/go/smallwebwaf/internal/requestlog"
-	"sneak.berlin/go/smallwebwaf/internal/waf"
 )
 
 // coreRuleSet inspects the request with the Core Rule Set, unless
@@ -18,7 +18,7 @@ import (
 // pathExempt decides, and notes the rules it matched and its score in the
 // log line, and the rules in the metrics. A score at or over
 // SWW_WAF_ANOMALY_THRESHOLD is a match: it adds the tag exploitsignature,
-// raises the waf_block alert, and in block mode refuses the request with 403,
+// raises the core_rule_set_match alert, and in block mode refuses the request with 403,
 // which is an offence its client's history counts. Its figures are the score
 // and the threshold.
 type coreRuleSet struct{}
@@ -38,12 +38,12 @@ func (coreRuleSet) check(_ context.Context, rq *request, _ time.Time) *verdict {
 	result, read, _ := rq.h.coreRuleSet.Inspect(rq.in, rq.client, rq.in.Body)
 	rq.requestBytes = int64(len(read))
 
-	rq.line.DurationWAF = new(requestlog.Milliseconds(time.Since(start)))
-	rq.line.WAFRuleIDs = result.RuleIDs
-	rq.line.WAFScore = &result.Score
+	rq.line.DurationCoreRuleSetMS = new(requestlog.Milliseconds(time.Since(start)))
+	rq.line.CoreRuleSetRuleIDs = result.RuleIDs
+	rq.line.CoreRuleSetScore = &result.Score
 
 	for _, id := range result.RuleIDs {
-		rq.h.metrics.WAFMatched(cfg.WAFMode, id)
+		rq.h.metrics.CoreRuleSetMatched(cfg.WAFMode, id)
 	}
 
 	threshold := cfg.WAFAnomalyThreshold
@@ -52,26 +52,26 @@ func (coreRuleSet) check(_ context.Context, rq *request, _ time.Time) *verdict {
 	}
 
 	rq.addTag(config.ExploitSignatureTag)
-	rq.alertWAFBlock(result)
+	rq.alertCoreRuleSetMatch(result)
 
 	if cfg.WAFMode == config.WAFModeDetect {
 		return nil
 	}
 
-	rq.wafBlocked = true
+	rq.blockedByCoreRuleSet = true
 
 	return &verdict{
-		action:  requestlog.ActionWAFBlocked,
+		action:  requestlog.ActionBlockedByCoreRuleSet,
 		figures: map[string]any{figureScore: result.Score, "threshold": threshold},
 	}
 }
 
-// alertWAFBlock raises the waf_block alert for the request, which the Core
-// Rule Set scored at result, at or over SWW_WAF_ANOMALY_THRESHOLD. Its
+// alertCoreRuleSetMatch raises the core_rule_set_match alert for the request,
+// which the Core Rule Set scored at result, at or over SWW_WAF_ANOMALY_THRESHOLD. Its
 // detail gives the rule ids, the score, the method and the path with the
 // query, and, for a request that is not refused for it, the mode: detect,
 // or observe in observe mode.
-func (rq *request) alertWAFBlock(result waf.Result) {
+func (rq *request) alertCoreRuleSetMatch(result coreruleset.Result) {
 	detail := map[string]any{
 		"rule_ids": result.RuleIDs,
 		"score":    result.Score,
@@ -87,7 +87,7 @@ func (rq *request) alertWAFBlock(result waf.Result) {
 	}
 
 	rq.h.alerts.Raise(alerts.Alert{
-		Event:    alerts.EventWAFBlock,
+		Event:    alerts.EventCoreRuleSetMatch,
 		Host:     rq.site,
 		Client:   rq.client,
 		Netblock: rq.h.clientGroup(rq.client),