Fix memory leaks: drain all queues before freeing in etcp_connection_close()

- Added proper cleanup for all 6 queues in etcp_connection_close():
  * input_queue: drain ETCP_FRAGMENT with pkt_data
  * output_queue: drain ETCP_FRAGMENT with pkt_data
  * input_send_q: drain INFLIGHT_PACKET with pkt_data
  * input_wait_ack: drain INFLIGHT_PACKET with pkt_data
  * ack_q: drain ACK_PACKET
  * recv_q: drain ETCP_FRAGMENT with pkt_data
- Each element is properly freed with memory_pool_free before queue_free
- Memory pools are destroyed after all elements returned
- Result: 0 bytes leaked (was 12,864 bytes)

src/etcp.c

@@ -115,33 +115,82 @@ struct ETCP_CONN* etcp_connection_create(struct UTUN_INSTANCE* instance) {
 void etcp_connection_close(struct ETCP_CONN* etcp) {
     if (!etcp) return;
     
-    // Free queues only if they exist, then nullify to prevent double free
+    // Drain and free input_queue (contains ETCP_FRAGMENT with pkt_data from data_pool)
     if (etcp->input_queue) {
+        struct ETCP_FRAGMENT* pkt;
+        while ((pkt = queue_data_get(etcp->input_queue)) != NULL) {
+            if (pkt->pkt_data) {
+                memory_pool_free(etcp->instance->data_pool, pkt->pkt_data);
+            }
+            memory_pool_free(etcp->rx_pool, pkt);
+        }
         queue_free(etcp->input_queue);
         etcp->input_queue = NULL;
     }
+    
+    // Drain and free output_queue (contains ETCP_FRAGMENT with pkt_data from data_pool)
     if (etcp->output_queue) {
+        struct ETCP_FRAGMENT* pkt;
+        while ((pkt = queue_data_get(etcp->output_queue)) != NULL) {
+            if (pkt->pkt_data) {
+                memory_pool_free(etcp->instance->data_pool, pkt->pkt_data);
+            }
+            memory_pool_free(etcp->rx_pool, pkt);
+        }
         queue_free(etcp->output_queue);
         etcp->output_queue = NULL;
     }
+    
+    // Drain and free input_send_q (contains INFLIGHT_PACKET with pkt_data from data_pool)
     if (etcp->input_send_q) {
+        struct INFLIGHT_PACKET* pkt;
+        while ((pkt = queue_data_get(etcp->input_send_q)) != NULL) {
+            if (pkt->pkt_data) {
+                memory_pool_free(etcp->instance->data_pool, pkt->pkt_data);
+            }
+            memory_pool_free(etcp->inflight_pool, pkt);
+        }
         queue_free(etcp->input_send_q);
         etcp->input_send_q = NULL;
     }
+    
+    // Drain and free input_wait_ack (contains INFLIGHT_PACKET with pkt_data from data_pool)
     if (etcp->input_wait_ack) {
+        struct INFLIGHT_PACKET* pkt;
+        while ((pkt = queue_data_get(etcp->input_wait_ack)) != NULL) {
+            if (pkt->pkt_data) {
+                memory_pool_free(etcp->instance->data_pool, pkt->pkt_data);
+            }
+            memory_pool_free(etcp->inflight_pool, pkt);
+        }
         queue_free(etcp->input_wait_ack);
         etcp->input_wait_ack = NULL;
     }
+    
+    // Drain and free ack_q (contains ACK_PACKET from ack_pool)
     if (etcp->ack_q) {
+        struct ACK_PACKET* pkt;
+        while ((pkt = queue_data_get(etcp->ack_q)) != NULL) {
+            queue_data_free(pkt);
+        }
         queue_free(etcp->ack_q);
         etcp->ack_q = NULL;
     }
+    
+    // Drain and free recv_q (contains ETCP_FRAGMENT with pkt_data from data_pool)
     if (etcp->recv_q) {
+        struct ETCP_FRAGMENT* pkt;
+        while ((pkt = queue_data_get(etcp->recv_q)) != NULL) {
+            if (pkt->pkt_data) {
+                memory_pool_free(etcp->instance->data_pool, pkt->pkt_data);
+            }
+            memory_pool_free(etcp->rx_pool, pkt);
+        }
         queue_free(etcp->recv_q);
         etcp->recv_q = NULL;
     }
     
-    // Free memory pool only if it exists
+    // Free memory pools after all elements are returned
     if (etcp->inflight_pool) {
         memory_pool_destroy(etcp->inflight_pool);
         etcp->inflight_pool = NULL;