Boost.Nowide: Environment variable API and other functions fail with UTF-8 input

Boost.Nowide: Environment variable API and other functions fail with UTF-8 input: a task in LegoFlow-SWE (Harbor dataset). After enabling the full test suite (compiling and running code that was previously skipped or compiled but never executed), several functions in Boost.Nowide exhibit incorrect…

The task

After enabling the full test suite (compiling and running code that was previously skipped or compiled but never executed), several functions in Boost.Nowide exhibit incorrect behavior when handling UTF-8 strings, error conditions, and platform-specific semantics.

Part of Lego-X/LegoFlow-SWE.