Add etcp_socket_add uasync integration for packet reception

src/etcp_connections.c

@@ -263,6 +263,10 @@ struct ETCP_SOCKET* etcp_socket_add(struct UTUN_INSTANCE* instance, struct socka
     
     // Add to instance's socket list
     e_sock->next = instance->etcp_sockets;
+    // Register socket with uasync for receiving packets
+    e_sock->socket_id = uasync_add_socket(instance->ua, e_sock->fd,
+                                          etcp_connections_read_callback,
+                                          NULL, NULL, e_sock);
     instance->etcp_sockets = e_sock;
     
     return e_sock;

src/etcp_connections.h

@@ -38,6 +38,7 @@ struct ETCP_SOCKET {
     int errorcode;
     size_t pkt_format_errors;
     
+    void* socket_id;        // Socket ID from uasync_add_socket
 };
 
 // ETCP Link - одно динамическое соединение (один путь)