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/lookup_test.go

@@ -94,9 +94,9 @@ func TestRequestThatWaitedForItsLookupIsCountedWhenItGoesOn(t *testing.T) {
 	clk := &clock{now: time.Date(2026, 10, 6, 0, 0, 58, 0, time.UTC)}
 	addr, out, server := startProxyWithClock(t, app.URL, geojsURL, clk.Now,
 		map[string]string{
-			trustedProxies:  trustLocalhost,
-			lookupTimeout:   "1h",
-			deniedCountries: "kp",
+			trustedProxies: trustLocalhost,
+			lookupTimeout:  "1h",
+			tagDeny:        denyKP,
 		})
 
 	requestFromDE := func() *http.Request {