fix: fail closed on StringLookup external vocab metadata

[mldangelo-oai]

Summary

• mark fixed-version external StringLookup vocabulary findings as inconclusive metadata-only coverage
• add exit-code regressions for fixed metadata, unknown metadata, vulnerable CVE attribution, and benign inline vocabularies
• update the root changelog

Validation

• Focused StringLookup slice: 7 passed
• Full tests/scanners/test_keras_zip_scanner.py: 162 passed
• ruff format/check for touched files
• mypy modelaudit/scanners/keras_zip_scanner.py tests/scanners/test_keras_zip_scanner.py
• git diff --check

[mldangelo-oai]

@codex review

[github-actions]

Workflow run and artifacts

Performance Benchmarks

Compared 12 shared benchmarks with a regression threshold of 15%.
Status: 0 regressions, 0 improved, 12 stable, 0 new, 0 missing.
Aggregate shared-benchmark median: 1.192s -> 1.195s (+0.2%).

Workload	Benchmark	Target	Size	Files	Baseline	Current	Change	Status
suspicious-pickle-intake	tests/benchmarks/test_scan_benchmarks.py::test_scan_suspicious_pickle_intake	suspicious-intake	183.8 KiB	4	123.97ms	126.44ms	+2.0%	stable
padded-multi-stream-upload	tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_padded_multi_stream_upload	multi_stream_padded	4.1 KiB	1	1.37ms	1.34ms	-1.6%	stable
direct-malicious-upload	tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_direct_malicious_upload	malicious_reduce	52 B	1	1.28ms	1.26ms	-1.4%	stable
mixed-model-repository	tests/benchmarks/test_scan_benchmarks.py::test_scan_release_candidate_repository	release-candidate	547.3 KiB	32	372.78ms	377.26ms	+1.2%	stable
nested-payload-review	tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_nested_payload_review[nested_base64]	nested_base64	98 B	1	403.1us	407.5us	+1.1%	stable
warm-cache-rescan	tests/benchmarks/test_scan_benchmarks.py::test_scan_warm_cached_repository_rescan	release-candidate	547.3 KiB	32	57.88ms	57.38ms	-0.9%	stable
nested-payload-review	tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_nested_payload_review[nested_raw]	nested_raw	78 B	1	398.0us	401.3us	+0.8%	stable
clean-training-checkpoint	tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_clean_training_checkpoint	safe_large	278.2 KiB	1	107.16ms	106.31ms	-0.8%	stable
duplicate-heavy-registry	tests/benchmarks/test_scan_benchmarks.py::test_scan_duplicate_registry_snapshot	registry-snapshot	915.2 KiB	13	356.06ms	353.37ms	-0.8%	stable
nested-payload-review	tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_nested_payload_review[nested_hex]	nested_hex	130 B	1	407.2us	409.4us	+0.5%	stable
chunked-upload-stream	tests/benchmarks/test_picklescan_benchmarks.py::test_picklescan_chunked_upload_stream	chunked_stream	278.2 KiB	1	109.67ms	109.10ms	-0.5%	stable
single-checkpoint-preflight	tests/benchmarks/test_scan_benchmarks.py::test_scan_single_checkpoint_before_load	single_checkpoint.pkl	183.0 KiB	1	60.66ms	60.96ms	+0.5%	stable

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. You're on a roll.

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[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 6b521ef08c

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[ianw-oai]

Reviewed; this looks acceptable.