Take Brazilian AS details from NIC.br's WHOIS server (closes #174)

LACNIC's answer for an AS that NIC.br registers is NIC.br's answer with
each accented letter replaced by U+FFFD, so a name such as AS52751's
cannot be recovered from it. When LACNIC's answer carries NIC.br's
copyright notice, the client now also asks whois.registro.br for the AS
and takes the fields from that answer, which is Latin-1 and decoded as
before. When that query fails, when the answer has no fields, or when
NIC.br says the client is over its query limit, LACNIC's fields are kept
and a warning is logged. After an over-limit answer the client skips
NIC.br for an hour. The tests use recorded answers for AS52751.

Model: opus-5-5

internal/routewatch/asnfetcher.go

@@ -68,10 +68,12 @@ type ASNFetcher struct {
 
 // NewASNFetcher creates a new ASN fetcher.
 func NewASNFetcher(db database.Store, logger *slog.Logger) *ASNFetcher {
+	logger = logger.With("component", "asn_fetcher")
+
 	return &ASNFetcher{
 		db:              db,
-		whoisClient:     whois.NewClient(),
-		logger:          logger.With("component", "asn_fetcher"),
+		whoisClient:     whois.NewClient(logger),
+		logger:          logger,
 		immediateQueue:  make(chan int, immediateQueueSize),
 		stopCh:          make(chan struct{}),
 		done:            make(chan struct{}),