fix: CLI ErrorCode reuse + result_type→renderer parity contract test #305

Job	Run time
Frontend unit tests (vitest) (macos-latest)	39s
Frontend unit tests (vitest) (ubuntu-latest)	29s
ruff + pip-audit (ubuntu-latest)	28s
Frontend unit tests (vitest) (windows-latest)	1m 13s
pytest (ubuntu-latest)	55s
pytest (windows-latest)	1m 22s
ruff + pip-audit (macos-latest)	20s
mypy	20s
pytest (macos-latest)	40s
API integration tests + coverage (macos-latest)	15s
Verify prod requirements.txt is sufficient	13s
API integration tests + coverage (windows-latest)	53s
Performance benchmarks (gated)	34s
ruff + pip-audit (windows-latest)	1m 11s
API integration tests + coverage (ubuntu-latest)	23s
	9m 55s

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