feat: ETCP trace logging — ETCP_SEND, ETCP_RECV, SEND_Q_DRAIN, SEND_Q_ACKED, CONSUMER_ACK, ACK_SEND

Six key log points at DEBUG level to trace the full ACK chain:
  ETCP_SEND  — server sends direction A data
  ETCP_RECV  — received any svc_route packet
  SEND_Q_DRAIN — send_q drained after client ACK
  SEND_Q_ACKED — server received client ACK (direction A)
  CONSUMER_ACK  — server sends consumer ACK (direction B)
  ACK_SEND      — low-level ACK packet sent

src/etcp_router.c

@@ -78,9 +78,10 @@ static int router_send_one_flags(struct ETCP_ROUTER_CONN* rconn, const uint8_t*
         queue_entry_free(entry); queue_dgram_free(entry); if (!seq_flags) rconn->tx_seq--; return -1;
     }
     rconn->last_dgram_ts = get_current_timestamp();
-    DEBUG_TRACE(DEBUG_CATEGORY_ETCPROUTE, "router_send: seq=%u → %016llx svc_id=%u len=%zu inflight=%d",
-                seq, (unsigned long long)rconn->remote_node_id, rconn->svc_id, pl_len,
-                (int32_t)(rconn->tx_seq - rconn->tx_acked));
+    DEBUG_DEBUG(DEBUG_CATEGORY_ETCPROUTE, "ETCP_SEND: svc_id=%u seq=%u len=%zu inflight=%d → %016llx",
+                rconn->svc_id, seq, pl_len,
+                (int32_t)(rconn->tx_seq - rconn->tx_acked),
+                (unsigned long long)rconn->remote_node_id);
     return etcp_send(conn, entry);
 }
 
@@ -149,6 +150,9 @@ static void router_close_and_notify(struct ETCP_ROUTER_CONN* rconn) {
 }
 
 static void router_drain_send_q(struct ETCP_ROUTER_CONN* rconn) {
+    int sq = queue_entry_count(rconn->send_q);
+    if (sq > 0) DEBUG_DEBUG(DEBUG_CATEGORY_ETCPROUTE, "SEND_Q_DRAIN: svc_id=%u send_q=%d inflight=%d",
+                             rconn->svc_id, sq, (int32_t)(rconn->tx_seq - rconn->tx_acked));
     while (1) {
         if ((int32_t)(rconn->tx_seq - rconn->tx_acked) >= ROUTER_MAX_INFLIGHT) break;
         struct ll_entry* e = queue_data_get(rconn->send_q);
@@ -224,8 +228,8 @@ static void router_send_ack(struct ETCP_ROUTER_CONN* rconn) {
     entry->dgram = (uint8_t*)hdr;
     entry->len   = SVC_ROUTE_HDR_SIZE;
 
-    DEBUG_DEBUG(DEBUG_CATEGORY_ETCPROUTE, "router_ack: → %016llx svc_id=%u rx_seq=%u",
-                (unsigned long long)rconn->remote_node_id, rconn->svc_id, rconn->rx_seq);
+    DEBUG_DEBUG(DEBUG_CATEGORY_ETCPROUTE, "ACK_SEND: svc_id=%u rx_seq=%u → %016llx",
+                rconn->svc_id, rconn->rx_seq, (unsigned long long)rconn->remote_node_id);
     etcp_send(conn, entry);
 }
 
@@ -325,6 +329,9 @@ static void etcp_router_recv_cb(struct ETCP_CONN* conn, struct ll_entry* entry)
     size_t                pl_len = entry->len - SVC_ROUTE_HDR_SIZE;
     uint8_t*              pl     = entry->dgram + SVC_ROUTE_HDR_SIZE;
 
+    DEBUG_DEBUG(DEBUG_CATEGORY_ETCPROUTE, "ETCP_RECV: svc_id=%u seq=%u len=%zu from %016llx",
+                hdr->svc_id, hdr->seq, pl_len, (unsigned long long)hdr->src_node_id);
+
     if (hdr->dst_node_id == inst->node_id) {
         // ========== Мы — целевая нода ==========
         struct ETCP_ROUTER_CONN* rconn = router_conn_find(inst, hdr->src_node_id, hdr->svc_id);
@@ -340,6 +347,10 @@ static void etcp_router_recv_cb(struct ETCP_CONN* conn, struct ll_entry* entry)
             if (rconn) {
                 if ((int32_t)(hdr->seq - rconn->tx_acked) >= 0) {
                     rconn->tx_acked = hdr->seq;
+                    DEBUG_DEBUG(DEBUG_CATEGORY_ETCPROUTE, "SEND_Q_ACKED: svc_id=%u ack=%u inflight=%d send_q=%d from %016llx",
+                                rconn->svc_id, hdr->seq, (int32_t)(rconn->tx_seq - rconn->tx_acked),
+                                queue_entry_count(rconn->send_q),
+                                (unsigned long long)hdr->src_node_id);
                 } else {
                     DEBUG_WARN(DEBUG_CATEGORY_ETCPROUTE, "router: stale ACK seq=%u tx_acked=%u from %016llx, ignoring",
                                hdr->seq, rconn->tx_acked, (unsigned long long)hdr->src_node_id);
@@ -557,6 +568,8 @@ void etcp_router_consumer_ack(struct UTUN_INSTANCE* inst, uint64_t remote_node_i
     struct ETCP_ROUTER_CONN* rconn = etcp_router_conn_get(inst, remote_node_id, svc_id);
     if (!rconn) return;
     rconn->consumer_ack = 1;
+    DEBUG_DEBUG(DEBUG_CATEGORY_ETCPROUTE, "CONSUMER_ACK: svc_id=%u rx_seq=%u → %016llx",
+                svc_id, rconn->rx_seq, (unsigned long long)remote_node_id);
     router_ack_do_send(rconn);
 }