refactor: move transport (etcp/stcp/normalizer) to transport_layer/, routing (bgp/pings/topo*) to routing_layer/

tests/test_stream_cipher.c

@@ -1,5 +1,5 @@
 // test_stream_cipher.c — tests for streaming cipher (AES-128-CTR)
-#include "../src/secure_channel.h"
+#include "secure_channel.h"
 #include "../lib/debug_config.h"
 #include <stdio.h>
 #include <string.h>