fix: add missing includes for dispatcher and transport in test_engine.c

Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>

test_engine.c

@@ -3,6 +3,8 @@
 #include <string.h>
 #include <assert.h>
 #include <stdatomic.h>
+#include "dispatcher.h"
+#include "transport.h"
 #include "engine.h"
 
 // Test helper