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_test.go

@@ -93,6 +93,20 @@ func TestEachRuleAction(t *testing.T) {
 	s.get(client, http.StatusTooManyRequests, requestlog.ActionBanned)
 }
 
+func TestEachRuleActionAddsTheExploitSignatureTag(t *testing.T) {
+	t.Parallel()
+
+	s, _, _ := startWithClock(t, "", map[string]string{
+		rulesDir: writeRules(t, "noted path log ^/noted$\n"+testRules),
+	})
+
+	wantTags(t, s.request(client, "/noted", http.StatusOK, requestlog.ActionForward),
+		"exploitsignature")
+	wantTags(t, s.request(client, "/blocked", http.StatusForbidden,
+		requestlog.ActionRuleBlocked), "exploitsignature")
+	wantTags(t, s.get(client, http.StatusOK, requestlog.ActionForward))
+}
+
 func TestRuleRefusalNamesItsHeuristicAndTheRule(t *testing.T) {
 	t.Parallel()