feat(hex): without overloading; fix(sha256): const uint8_t * -> uint8_t *

include/base/hex.hpp

@@ -0,0 +1,12 @@
+#pragma once
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace hex
+{
+    bool isValid(const std::string &str) noexcept;
+    std::string encode(const std::vector<uint8_t> &data) noexcept;
+    std::vector<uint8_t> decode(const std::string &str);
+}