chatgui: fix duplicate connection on invite when node already connected

- chat_core_has_conn: search all connections (pending+ready) by peer_node_id
- chat_core_connect_from_invite: skip chat_core_connect_auto if already connected
- ca_timeout_cb: close timed-out connection to free socket link slot
  + cancel remaining timers + ca_cleanup on all-failed

tools/chatgui/transport/chat_core.c

@@ -582,6 +582,18 @@ int chat_core_load_nodeinfo(uint64_t node_id, uint8_t* buf, size_t buf_size,
 
 /* ─── подключение к пиру из invite-ссылки ─── */
 
+/* проверить, есть ли уже ETCP-подключение к узлу (готовое или pending) */
+static int chat_core_has_conn(uint64_t node_id) {
+    if (!g_cc.inst || !g_cc.inst->connections) return 0;
+    struct ll_entry* entry = g_cc.inst->connections->head;
+    while (entry) {
+        struct conn_queue_entry* ce = (struct conn_queue_entry*)entry->data;
+        if (ce->conn->peer_node_id == node_id) return 1;
+        entry = entry->next;
+    }
+    return 0;
+}
+
 static void connect_result_cb(int result, uint64_t node_id, void* arg) {
     uint64_t channel_id = arg ? *(uint64_t*)arg : 0;
     uint8_t data[20];
@@ -636,6 +648,13 @@ void chat_core_connect_from_invite(struct chat_invite* inv) {
         }
     }
 
+    if (chat_core_has_conn(node_id)) {
+        DEBUG_INFO(DEBUG_CATEGORY_CONNECTIVITY, "%s: invite node 0x%016llx already connected, reusing",
+                   CC_ID, (unsigned long long)node_id);
+        connect_result_cb(CC_OK, node_id, &inv->channel_id);
+        return;
+    }
+
     DEBUG_INFO(DEBUG_CATEGORY_CONNECTIVITY, "%s: invite saved node=0x%016llx addrs=%d, starting direct connect",
                CC_ID, (unsigned long long)node_id, inv->addr_count);
 
@@ -700,9 +719,17 @@ static void ca_timeout_cb(void* arg) {
     st->pending_count--;
     DEBUG_DEBUG(DEBUG_CATEGORY_CONNECTIVITY, "%s: auto_connect TIMEOUT idx=%d pending=%d/%d peer=0x%016llx",
                 CC_ID, ctx->addr_index, st->pending_count, st->addr_count, (unsigned long long)st->node_id);
+    if (st->conns[ctx->addr_index]) {
+        etcp_connection_close(st->conns[ctx->addr_index]);
+        st->conns[ctx->addr_index] = NULL;
+    }
     if (st->pending_count <= 0 && !st->delivered) {
         st->delivered = 1;
+        for (int i = 0; i < st->addr_count; i++) {
+            if (st->timers[i]) { uasync_cancel_timeout(st->inst->ua, st->timers[i]); st->timers[i] = NULL; }
+        }
         st->result_cb(CC_ERR_TIMEOUT, st->node_id, st->result_arg);
+        ca_cleanup(st);
     }
 }