fix(harness): retry timed-out Codex steps

scripts/execute.py

@@ -343,6 +343,23 @@ class StepExecutor:
                 env=environment,
                 timeout=1800,
             )
+        except subprocess.TimeoutExpired as exc:
+            stdout = exc.stdout or ""
+            stderr = exc.stderr or ""
+            if isinstance(stdout, bytes):
+                stdout = stdout.decode("utf-8", errors="replace")
+            if isinstance(stderr, bytes):
+                stderr = stderr.decode("utf-8", errors="replace")
+            timeout_message = (
+                f"Codex timed out after {exc.timeout} seconds."
+            )
+            stderr = f"{stderr}\n{timeout_message}".strip()
+            result = subprocess.CompletedProcess(
+                command,
+                returncode=124,
+                stdout=stdout,
+                stderr=stderr,
+            )
         except FileNotFoundError as exc:
             raise CodexEnvironmentError(
                 "Codex CLI를 찾을 수 없습니다. codex를 설치하고 PATH를 확인하세요."