keepalive handshake: device_type + keepalive negotiation in UDP/TCP INIT

- Добавлен device_type (1 байт, CLIENT_TYPE_*) в INIT_REQUEST и INIT_RESPONSE
- Добавлен keepalive_interval (2 байта) в INIT_RESPONSE
- STCP handshake расширен с 43 до 46 байт (device_type+keepalive)
- negotiate_keepalive(): оба desktop/server → min, иначе (есть mobile) → max
- keepalive_interval вынесен в UTUN_INSTANCE для использования в handshake
- stcp_client_connect() принимает device_type и keepalive_interval
- peer_device_type/peer_keepalive_interval передаются через stcp_link в ETCP_LINK

tools/chatgui/transport/utun_node.cpp

@@ -217,19 +217,20 @@ QList<NodeAddr> UtunNode::getInviteAddresses(DbManager* db) {
 
         /* 3) TCP from local TCP sockets */
         {
-            struct ETCP_SOCKET* ts = m_instance->tcp_sockets;
-            while (ts) {
-                struct sockaddr_storage* sa = &ts->interface_addr;
+            struct ETCP_SOCKET* s = m_instance->etcp_sockets;
+            while (s) {
+                if (!s->is_tcp) { s = s->next; continue; }
+                struct sockaddr_storage* sa = &s->interface_addr;
                 if (sa->ss_family == AF_INET) {
                     struct sockaddr_in* sin = (struct sockaddr_in*)sa;
                     QByteArray addr((const char*)&sin->sin_addr, 4);
-                    add_addr(addr, ntohs(sin->sin_port), 4, (int)ts->sock_id, INVITE_PROTO_TCP);
+                    add_addr(addr, ntohs(sin->sin_port), 4, (int)s->sock_id, INVITE_PROTO_TCP);
                 } else if (sa->ss_family == AF_INET6) {
                     struct sockaddr_in6* sin6 = (struct sockaddr_in6*)sa;
                     QByteArray addr((const char*)&sin6->sin6_addr, 16);
-                    add_addr(addr, ntohs(sin6->sin6_port), 6, (int)ts->sock_id, INVITE_PROTO_TCP);
+                    add_addr(addr, ntohs(sin6->sin6_port), 6, (int)s->sock_id, INVITE_PROTO_TCP);
                 }
-                ts = ts->next;
+                s = s->next;
             }
         }