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/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 {