test(cleanup): Remove obsolete timeout restart xfail

The test_run_result_timeout_triggers_restart xfail was a placeholder
added before ScriptedStdout/Stdin infrastructure existed. The exact
behavior it intended to test is already covered by the parametrized
test_run_result_retries_with_process_factory test case
"timeout_then_retry_succeeds" (lines 537-542, 556-606).

Author: tony

tests/test_control_mode_engine.py

@@ -658,28 +658,3 @@ def test_notifications_overflow_then_iter(case: BackpressureFixture) -> None:
         notif = next(engine.iter_notifications(timeout=0.1), None)
         assert notif is not None
         assert notif.kind.name == "SESSIONS_CHANGED"
-
-
-class TimeoutRestartFixture(t.NamedTuple):
-    """Fixture for per-command timeout restart behavior."""
-
-    test_id: str
-
-
-@pytest.mark.xfail(
-    reason="per-command timeout restart needs injectable control-mode transport",
-    strict=False,
-)
-@pytest.mark.parametrize(
-    "case",
-    [
-        TimeoutRestartFixture(test_id="timeout_triggers_restart_then_succeeds"),
-    ],
-    ids=lambda c: c.test_id,
-)
-def test_run_result_timeout_triggers_restart(case: TimeoutRestartFixture) -> None:
-    """Placeholder: timeout should restart control process and allow next command."""
-    _ = ControlModeEngine(command_timeout=0.0001)
-    pytest.xfail(
-        "control-mode needs injectable process to simulate per-call timeout",
-    )