Fix: Segfault in test_routing_mesh during cleanup

In pn_deinit(), cancel waiter on etcp->input_queue and clear callback
on etcp->output_queue before freeing PKTNORM structure. This prevents
use-after-free when drain_and_free_fragment_queue() triggers
check_waiters() during etcp_connection_close().

src/pkt_normalizer.c

@@ -108,6 +108,17 @@ void pn_deinit(struct PKTNORM* pn) {
         queue_entry_free(pn->recvpart);
     }
 
+    // Cancel waiter and clear callbacks on ETCP queues to prevent use-after-free
+    // during etcp_connection_close() when drain_and_free_fragment_queue() is called
+    if (pn->etcp) {
+        if (pn->etcp->input_queue) {
+            queue_cancel_wait(pn->etcp->input_queue, &pn->etcp->input_queue->waiter);
+        }
+        if (pn->etcp->output_queue) {
+            queue_set_callback(pn->etcp->output_queue, NULL, NULL);
+        }
+    }
+
     free(pn);
 }