fix: use windows sandbox fallback for harness

tests/test_execute.py

@@ -34,6 +34,9 @@ def test_invoke_codex_uses_utf8_for_unicode_prompt(tmp_path, monkeypatch):
 
     assert "Euler–Bernoulli 보" in invocation["kwargs"]["input"]
     assert invocation["kwargs"]["encoding"] == "utf-8"
+    if execute.os.name == "nt":
+        config_index = invocation["command"].index("-c")
+        assert invocation["command"][config_index + 1] == 'windows.sandbox="unelevated"'
 
 
 def test_run_git_decodes_output_as_utf8(tmp_path, monkeypatch):