Record unique acknowledged packets at the instance transport boundary

src/Makefile.am

@@ -64,6 +64,8 @@ utun_CORE_SOURCES = \
 	tun_freebsd.c \
 	tun_windows.c \
 	transport_layer/etcp.c \
+	transport_layer/etcp_tx_stats.c \
+	transport_layer/etcp_tx_stats.h \
 	transport_layer/etcp_padding.c \
 	transport_layer/etcp_padding.h \
 	transport_layer/etcp_session.c \

src/transport_layer/etcp.c

@@ -1549,6 +1549,7 @@ void etcp_ack_recv(struct ETCP_CONN* etcp, uint32_t seq, uint16_t ts, uint16_t d
         DEBUG_TRACE(DEBUG_CATEGORY_ETCP, "packet seq=%u not found in wait_ack queue", seq);
         return;
     }
+    etcp_tx_record_ack(&etcp->instance->tx_history, get_time_us(), acked_pkt->ll.len);
 
     // === subtract inflight from the LAST link the packet was sent on ===
     if (acked_pkt->last_link && acked_pkt->last_link->bbr) {

src/utun_instance.h

@@ -20,6 +20,7 @@ extern "C" {
 #include "etcp_padding.h"
 #include "reality_io.h"
 #include "etcp_api.h"
+#include "transport_layer/etcp_tx_stats.h"
 #include "config_parser.h"
 #include "stcp_link.h"
 #include "firewall.h"
@@ -122,6 +123,7 @@ struct peer_sleep_cbk_entry {
 
 // Состояние одного узла. Вложенные модули освобождаются через их lifecycle API.
 struct UTUN_INSTANCE {
+    struct etcp_tx_history tx_history;
     struct reality_owner reality_owner;
     uint8_t core_started, utun_started, chat_started; // успешный запуск ядра / UTUN / чата