fix: configure harness console as utf-8

tests/test_execute.py

@@ -59,3 +59,22 @@ def test_feature_commit_message_is_windows_console_safe():
     )
 
     message.encode("cp949")
+
+
+def test_configure_utf8_stdio_reconfigures_both_streams(monkeypatch):
+    class ReconfigurableStream:
+        def __init__(self):
+            self.encodings = []
+
+        def reconfigure(self, *, encoding):
+            self.encodings.append(encoding)
+
+    stdout = ReconfigurableStream()
+    stderr = ReconfigurableStream()
+    monkeypatch.setattr(execute.sys, "stdout", stdout)
+    monkeypatch.setattr(execute.sys, "stderr", stderr)
+
+    execute._configure_utf8_stdio()
+
+    assert stdout.encodings == ["utf-8"]
+    assert stderr.encodings == ["utf-8"]