feat: add necessary includes for TCP probing functionality

src/DomainDiscovery.cpp

@@ -10,6 +10,16 @@
 // Minimal libcurl-based GET
 #include <curl/curl.h>
 
+// For TCP probe
+#include <sys/socket.h>
+#include <sys/select.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
 namespace {
 struct Buffer { std::string data; };