Fix int64_t/uint64_t conversion on Windows

The convertFromString<int64_t> and convertFromString<uint64_t>
functions were using 'long' and 'unsigned long' for parsing.
On Windows, these types are 32-bit, causing conversion failures
for values that exceed the 32-bit range.

Changed to use int64_t/uint64_t directly for proper cross-platform
64-bit integer handling.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: facontidavide

src/basic_types.cpp

@@ -120,7 +120,7 @@ std::string convertFromString<std::string>(StringView str)
 template <>
 int64_t convertFromString<int64_t>(StringView str)
 {
-  long result = 0;
+  int64_t result = 0;
   const auto [ptr, ec] = std::from_chars(str.data(), str.data() + str.size(), result);
   std::ignore = ptr;
   if(ec != std::errc())
@@ -133,7 +133,7 @@ int64_t convertFromString<int64_t>(StringView str)
 template <>
 uint64_t convertFromString<uint64_t>(StringView str)
 {
-  unsigned long result = 0;
+  uint64_t result = 0;
   const auto [ptr, ec] = std::from_chars(str.data(), str.data() + str.size(), result);
   std::ignore = ptr;
   if(ec != std::errc())