Release retained STUN port history during final core destruction

src/utun_instance.c

@@ -408,6 +408,7 @@ void utun_instance_destroy(struct UTUN_INSTANCE *instance) {
     
     instance->running = 0;
     stun_nat_destroy(instance);
+    stun_nat_forget_ports(instance);
     etcp_padding_stop(&instance->padding);
     DEBUG_INFO(DEBUG_CATEGORY_SYS, "[DESTROY] A done — diagnose complete");
 

tests/test_stun_nat.c

@@ -220,6 +220,7 @@ static struct stun_nat_result wait_result(struct fixture* f) {
 /* Проверяет неизменность исходного fd, sockaddr, NAT-полей и отсутствие таймеров после destroy. */
 static void fixture_destroy(struct fixture* f) {
     stun_nat_destroy(&f->inst);
+    stun_nat_forget_ports(&f->inst);
     assert(!memcmp(&f->source, &f->original, sizeof(f->source)));
     struct sockaddr_storage addr = {0};
     socklen_t size = sizeof(addr);