On Windows the Hermes venv interpreter cannot CreateProcess a binary under
C:\Program Files\WindowsApps (WinError 5) even though the shell resolves it,
so `hermes computer-use doctor` died with a raw PermissionError traceback
from _open_mcp. Catch the spawn OSError and print what failed, why the tool
may still work (PATH resolves another copy), and the fix (reinstall outside
WindowsApps or HERMES_CUA_DRIVER_CMD), exit 2.