Fix LocalFree leak in error_wsaerror - #749

- release the buffer allocated by `FormatMessageA` using an exception-safe scope guard
- check both the formatting result and buffer before appending message text
- preserve existing successful WSA error output
- return a deterministic wrapper-only string when formatting fails
- add a focused Windows-only failure-path assertion

- Linux Release configure and build passed
- clang-format and git diff checks passed
- non-network UtilityTests passed
- full Linux unit run reached 1,955 passing assertions; eight socket assertions were blocked by sandbox network restrictions
- Windows-specific behavior remains to be validated by CI

Fixes quickfix#555