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/sww/sww_test.go

@@ -611,14 +611,14 @@ func TestLookupDatabaseReplacedWhileRunningTakesEffect(t *testing.T) {
 	writeLookupDatabase(t, path, "DE")
 
 	env := map[string]string{
-		listenAddr:             localhost + ":0",
-		stateDir:               t.TempDir(),
-		rulesDir:               t.TempDir(),
-		metricsToken:           token,
-		instanceName:           instance,
-		lookupSource:           "file",
-		lookupDBPath:           path,
-		"SWW_DENIED_COUNTRIES": "kp",
+		listenAddr:     localhost + ":0",
+		stateDir:       t.TempDir(),
+		rulesDir:       t.TempDir(),
+		metricsToken:   token,
+		instanceName:   instance,
+		lookupSource:   "file",
+		lookupDBPath:   path,
+		"SWW_TAG_DENY": "country=KP",
 		// The requests sent until a replacement takes effect, and those
 		// for the metrics, must not break a rate limit, whose ban would
 		// refuse them too.
@@ -1280,7 +1280,7 @@ func wantStartingLine(t *testing.T, line map[string]any, dir string) {
 		"SWW_RATE_LIMIT_PER_HOUR":           "1500",
 		rateLimitPerDay:                     "6000",
 		"SWW_RATE_LIMIT_EXEMPT_PATHS":       "",
-		"SWW_DENIED_COUNTRIES":              "",
+		"SWW_TAG_DENY":                      "",
 		"SWW_EXCLUSIVELY_ALLOWED_COUNTRIES": "",
 		"SWW_BAN_RESPONSE":                  "403",
 		"SWW_LIMIT_BAN_DURATION":            "1h",