Two UI config tests (config_corrupt_file, config_missing_fields) used
Unix-only system("mkdir -p") to create test directories. On Windows this
fails with "The syntax of the command is incorrect." — replaced with the
portable cbm_mkdir_p() function already in compat_fs.h.
The /tmp/ → %TEMP%\ translation produces longer paths (~50 chars)
than the original templates (~25 chars). Changed all 68 test
declarations from char tmpdir[] = "..." (sized to literal) to
char tmpdir[256] with snprintf initialization.
- cbm_mkdtemp: _mktemp + _mkdir on Windows
- cbm_setenv/cbm_unsetenv: _putenv_s on Windows
- cbm_pipe: _pipe on Windows
- Replace bare POSIX calls in 12 test files with compat wrappers
- All test files now include compat.h