test: add golden render for all formats

tests/fixtures/codex_exec_json_all_formats.txt

@@ -0,0 +1,32 @@
+stream error: Failed to load optional config file ~/.codex/local.toml (ENOENT); continuing with defaults
+thread started
+turn started
+2. ✓ searched: python jsonlines parser handle unknown fields
+stream error: Web search disabled by policy; returned cached results only
+3. ▸ tool: github.search_issues
+3. ✓ tool: github.search_issues
+4. ▸ `pytest -q`
+4. ✗ `pytest -q` (exit 1)
+5. ✓ updated `src/compute_answer.py`, `tests/test_beta.py`
+6. ▸ `pytest -q`
+6. ✓ `pytest -q`
+7. Root cause: compute_answer() returned 0. Updated logic to return 42 for the valid input path. Re-ran pytest to confirm all tests pass.
+assistant:
+  I found the failing assertion in tests/test_beta.py and updated src/compute_answer.py to return the expected value (42). After the change, `pytest -q` reports 12 passed.
+turn completed
+turn started
+9. ▸ `npm test`
+9. ✗ `npm test` (exit 127)
+10. ✓ warning: Command `npm` not found in PATH (exit 127).
+turn failed: Aborted: required dependency `npm` is missing; cannot continue.
+stream error: codex exec exited non-zero (1) after turn.failed
+thread started
+turn started
+assistant:
+  Legacy schema example: hello (item_type=assistant_message).
+2. ✓ `echo legacy`
+turn completed
+thread started
+turn started
+2. ✓ updated `README.md`
+turn completed