IOBase.isatty() Missing closed Check

[ever0de]

Problem: The isatty() method does not check if the file is closed before returning False. CPython raises ValueError when called on closed files.

RustPython Location: crates/vm/src/stdlib/io.rs:480-482

#[pymethod]
fn isatty(_self: PyObjectRef) -> bool {
    false  // ✗ Missing closed check
}

CPython 3.14 Reference: Modules/_io/iobase.c:538-545

static PyObject *
_io__IOBase_isatty_impl(PyObject *self)
{
    if (iobase_check_closed(self))  // ✓ Checks if closed
        return NULL;
    Py_RETURN_FALSE;
}

[ever0de]

RustPython#7233