manage nonces in crypto.h

src/vault.h

@@ -1,7 +1,6 @@
 #pragma once
 
 #include "common.h"
-#include <array>
 #include <botan/secmem.h>
 #include <fstream>
 #include <optional>
@@ -11,10 +10,8 @@ constexpr u64 AFTER_HEADER_OFFSET = 68;
 
 // !!! REMEMBER TO UPDATE entry_total_size IN Vault::delete_file
 struct FileHeader {
-  std::array<u8, 24> name_nonce;
   u64 name_ciphertext_size;
   std::string name;
-  std::array<u8, 24> content_nonce;
   u64 content_ciphertext_size;
 };