Add unit tests for Utils::toHex

test/mocks/AES.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <stdint.h>
+#include <stddef.h>
+
+// Mock AES128 class for testing
+// Provides minimal interface to allow Utils.cpp to compile
+class AES128 {
+public:
+  void setKey(const uint8_t* key, size_t keySize) {}
+  void encryptBlock(uint8_t* output, const uint8_t* input) {}
+  void decryptBlock(uint8_t* output, const uint8_t* input) {}
+};