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

Each request gets tags, logged as `tags`: `asn=`, `country=`, one per `SWW_TAG_LISTS` list holding the client, `crowdsec`, `dnsbl=<zone>`, `abuseipdb` and `exploitsignature`. `SWW_TAG_DENY` refuses by tag and `SWW_TAG_LIMIT_PERCENT` lowers limits by tag. They replace `SWW_ASN_LIMIT_PERCENT`, `SWW_COUNTRY_LIMIT_PERCENT` and `SWW_DENIED_COUNTRIES`, with no aliases. A tag in those settings that nothing configured can give stops the start.

Judgement call: `SWW_ASN_LIMIT_PERCENT_URL` stays, its entries counting like `asn=` tags.
Judgement call: `SWW_TAG_LIMIT_PERCENT` also lowers byte limits, as the settings it replaces did.
Trips a reader: `sww_country_list_refusals_total` now counts only `SWW_EXCLUSIVELY_ALLOWED_COUNTRIES` refusals.

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}