Add IP information API with background WHOIS fetcher

- Add /ip and /ip/{addr} JSON endpoints returning comprehensive IP info
- Include ASN, netblock, country code, org name, abuse contact, RIR data
- Extend ASN schema with WHOIS fields (country, org, abuse contact, etc)
- Create background WHOIS fetcher for rate-limited ASN info updates
- Store raw WHOIS responses for debugging and data preservation
- Queue on-demand WHOIS lookups when stale data is requested
- Refactor handleIPInfo to serve all IP endpoints consistently

internal/server/server.go

@@ -13,13 +13,19 @@ import (
 	"github.com/go-chi/chi/v5"
 )
 
+// ASNFetcher is an interface for queuing ASN WHOIS lookups.
+type ASNFetcher interface {
+	QueueImmediate(asn int)
+}
+
 // Server provides HTTP endpoints for status monitoring
 type Server struct {
-	router   *chi.Mux
-	db       database.Store
-	streamer *streamer.Streamer
-	logger   *logger.Logger
-	srv      *http.Server
+	router     *chi.Mux
+	db         database.Store
+	streamer   *streamer.Streamer
+	logger     *logger.Logger
+	srv        *http.Server
+	asnFetcher ASNFetcher
 }
 
 // New creates a new HTTP server
@@ -70,3 +76,8 @@ func (s *Server) Stop(ctx context.Context) error {
 
 	return s.srv.Shutdown(ctx)
 }
+
+// SetASNFetcher sets the ASN WHOIS fetcher for on-demand lookups.
+func (s *Server) SetASNFetcher(fetcher ASNFetcher) {
+	s.asnFetcher = fetcher
+}