fix: fail closed on pytorch zip timeouts

[mldangelo-oai]

Summary

• mark PyTorch ZIP timeout paths as analysis_incomplete with an inconclusive scan outcome
• finish timeout results unsuccessful so partial archive coverage is not reported as complete
• downgrade the timeout check itself to INFO while preserving fail-closed result semantics

Finding

Fixes finding 3: timeout returns a complete-looking result.

Validation

• PROMPTFOO_DISABLE_TELEMETRY=1 uv run pytest tests/scanners/test_pytorch_zip_scanner.py::test_pytorch_zip_timeout_marks_inconclusive --maxfail=1
• uv run ruff format --check modelaudit/ packages/modelaudit-picklescan/src packages/modelaudit-picklescan/tests tests/
• uv run ruff check modelaudit/ packages/modelaudit-picklescan/src packages/modelaudit-picklescan/tests tests/
• uv run mypy modelaudit/ packages/modelaudit-picklescan/src packages/modelaudit-picklescan/tests tests/
• PROMPTFOO_DISABLE_TELEMETRY=1 uv run pytest -n auto -m "not slow and not integration" --maxfail=1

[github-actions]

Workflow run and artifacts

Performance Benchmarks

Compared 19 shared benchmarks with a regression threshold of 15%.
Status: 0 regressions, 0 improved, 19 stable, 0 new, 0 missing.
Aggregate shared-benchmark median: 192.04ms -> 193.44ms (+0.7%).

Benchmark	Target	Size	Files	Baseline	Current	Change	Status
tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_safe_payloads[safe_small]	safe_small	68 B	1	53.2us	56.3us	+5.8%	stable
tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_nested_payloads[nested_raw]	nested_raw	78 B	1	95.6us	100.5us	+5.2%	stable
tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_multi_stream_padded_payload	multi_stream_padded	4.1 KiB	1	129.9us	136.4us	+5.0%	stable
tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_chunked_stream	chunked_stream	278.2 KiB	1	6.66ms	6.85ms	+2.9%	stable
tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_dangerous_global_payloads[stack_global]	stack_global	21 B	1	64.9us	66.7us	+2.7%	stable
tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_nested_payloads[nested_base64]	nested_base64	98 B	1	100.0us	102.7us	+2.7%	stable
tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_opcode_budget_tail_payload	opcode_budget_tail	14 B	1	69.4us	71.3us	+2.7%	stable
tests/benchmarks/test_scan_benchmarks.py::test_validate_file_type_pytorch_zip	state_dict.pt	1.5 MiB	1	50.0us	51.3us	+2.6%	stable
tests/benchmarks/test_scan_benchmarks.py::test_skip_filter_plain_text_files	-	4.6 KiB	256	13.51ms	13.84ms	+2.4%	stable
tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_dangerous_global_payloads[malicious_reduce]	malicious_reduce	52 B	1	75.1us	76.8us	+2.3%	stable
tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_hidden_suspicious_string_budget	hidden_suspicious_string	8.0 KiB	1	585.1us	593.0us	+1.4%	stable
tests/benchmarks/test_scan_benchmarks.py::test_detect_file_format_safe_pickle	safe_model.pkl	49.4 KiB	1	29.9us	30.3us	+1.3%	stable
tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_safe_payloads[safe_large]	safe_large	278.2 KiB	1	3.47ms	3.50ms	+1.0%	stable
tests/benchmarks/test_scan_benchmarks.py::test_scan_pytorch_zip	state_dict.pt	1.5 MiB	1	30.84ms	31.14ms	+1.0%	stable
tests/benchmarks/test_scan_benchmarks.py::test_scan_duplicate_directory	duplicate-corpus	840.0 KiB	81	47.47ms	47.87ms	+0.8%	stable
tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_nested_payloads[nested_hex]	nested_hex	130 B	1	106.9us	107.7us	+0.7%	stable
tests/benchmarks/test_scan_benchmarks.py::test_scan_safe_pickle	safe_model.pkl	49.4 KiB	1	11.78ms	11.81ms	+0.3%	stable
tests/benchmarks/test_scan_benchmarks.py::test_scan_mixed_directory	mixed-corpus	1.7 MiB	54	75.88ms	75.96ms	+0.1%	stable
tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_safe_payloads[long_benign_string]	long_benign_string	1.0 MiB	1	1.08ms	1.08ms	+0.0%	stable

[ianw-oai]

Looks good. Tight fail-closed timeout fix with direct regression coverage.