Request tags, with refusing and limits per tag (closes #175)

Each request gets sorted tags from the lookup, new address lists, the
reputation sources and the rule matches, logged as `tags`. New settings:
`SWW_TAG_LISTS`, `SWW_TAG_DENY`, `SWW_TAG_LIMIT_PERCENT`. They replace
`SWW_ASN_LIMIT_PERCENT`, `SWW_COUNTRY_LIMIT_PERCENT` and
`SWW_DENIED_COUNTRIES`. New heuristics `tag_lists` and `tag_deny`; the
latter runs before the rate limits and again after the Core Rule Set.

Model: opus-5-5

internal/discriminator/rulefiles.go

@@ -8,12 +8,14 @@ import (
 	"time"
 
 	"sneak.berlin/go/smallwebwaf/internal/bans"
+	"sneak.berlin/go/smallwebwaf/internal/config"
 	"sneak.berlin/go/smallwebwaf/internal/requestlog"
 	"sneak.berlin/go/smallwebwaf/internal/rules"
 )
 
 // ruleFiles checks the request against the rules of the rule files at now,
-// notes the ids of those it matches in the log line, and refuses the request
+// notes the ids of those it matches in the log line, adds the tag
+// exploitsignature when it matches any, and refuses the request
 // when the last rule it matches refuses it: with ActionRuleBlocked for a block
 // rule, and ActionBanned for a ban rule. A ban rule bans the client's netblock
 // for a clear sign of attack, or in observe mode raises the alert for the ban
@@ -35,6 +37,8 @@ func (ruleFiles) check(_ context.Context, rq *request, now time.Time) *verdict {
 		return nil
 	}
 
+	rq.addTag(config.ExploitSignatureTag)
+
 	// Only the last rule matched can refuse the request.
 	last := matched[len(matched)-1]
 	figures := map[string]any{"rule_id": last.ID, "rule_action": last.Action}