msvcrt.getch() returns EOF sentinel as data when no console is attached

Bug report

Bug description:

"msvcrt.getch() returns EOF sentinel as data when no console is attached" --body "## Summary

On Windows, `msvcrt.getch()` returns the CRT EOF sentinel as normal Python data when no console is attached, instead of raising `OSError`.

Reproducer

```powershell
PCbuild\amd64\python_d.exe -c "import ctypes, msvcrt, sys; ctypes.windll.kernel32.FreeConsole(); sys.exit(0 if msvcrt.getch() == b'\xff' else 1)"
echo $LASTEXITCODE \``

Actual result:
`$LASTEXITCODE` is `0`

This means `msvcrt.getch()` returned `b'\xff'` after `FreeConsole()`.

Expected behavior

If `_getch()` fails because no console is attached, the Python wrapper should raise `OSError` instead of returning `b'\xff'`.

Environment

• OS: Windows 11
• Build: CPython debug build
• Command used to build: `PCbuild\build.bat -c Debug`"

CPython versions tested on:

3.15

Operating systems tested on:

Windows

Linked PRs

• gh-149450

Comece pelo ponto de entrada msvcrt.getch() e reproduza o comportamento com o comando PCbuild/amd64/python_d.exe após FreeConsole(). Confirme que a ausência de um console não produz mais b'\xff' e, em vez disso, gera OSError; a issue lista o PR vinculado gh-149450, portanto verifique esse trabalho primeiro.