Use strtod_l for locale-independent float parsing in cli::Reader

std::from_chars for floating-point types is unavailable in Apple libc++.
std::strtod depends on the C locale (LC_NUMERIC), so "3.14" fails
under locales that use comma as decimal separator.
Use strtod_l with an explicit "C" locale on all platforms.
Windows uses _strtod_l/_create_locale, POSIX uses strtod_l/newlocale.

Author: Centimo

include/rfl/cli/Reader.hpp

@@ -3,6 +3,8 @@
 
 #include <charconv>
 #include <concepts>
+#include <clocale>
+#include <cstdlib>
 #include <map>
 #include <optional>
 #include <set>
@@ -57,18 +59,29 @@ rfl::Result<T> parse_value(
       "Could not cast '" + _str + "' to boolean for key '" + _path + "'.");
 }
 
+// std::from_chars for float/double is unavailable in Apple libc++.
+// std::strtod depends on the C locale (LC_NUMERIC), so "3.14" can fail
+// under locales that use comma as decimal separator.
+// Use strtod_l with an explicit "C" locale on all platforms for consistency.
 template <class T> requires (std::is_floating_point_v<T>)
 rfl::Result<T> parse_value(
     const std::string& _str, const std::string& _path
 ) noexcept {
-  T value;
-  const auto [ptr, ec] =
-      std::from_chars(_str.data(), _str.data() + _str.size(), value);
-  if (ec != std::errc() || ptr != _str.data() + _str.size()) {
+  char* end = nullptr;
+#ifdef _WIN32
+  const auto c_locale = _create_locale(LC_NUMERIC, "C");
+  const double value = _strtod_l(_str.c_str(), &end, c_locale);
+  _free_locale(c_locale);
+#else
+  const auto c_locale = newlocale(LC_NUMERIC_MASK, "C", nullptr);
+  const double value = strtod_l(_str.c_str(), &end, c_locale);
+  freelocale(c_locale);
+#endif
+  if (end != _str.c_str() + _str.size()) {
     return error(
         "Could not cast '" + _str + "' to floating point for key '" + _path + "'.");
   }
-  return value;
+  return static_cast<T>(value);
 }
 
 template <class T> requires (std::is_integral_v<T> && !std::same_as<T, bool>)