fix(tests): test_dedup_detected_from_prior_hash fails -- adapter reads pre_existing flag not find_doc_id_by_hash result #292

Summary

test_dedup_detected_from_prior_hash in tests/test_adapters.py at line ~496 asserts outcome.deduplicated is True. But PipelineIngestor reads result.get("pre_existing", False) from the pipeline result, not from find_doc_id_by_hash. fake_ingest result dict has no 'pre_existing' key, so deduplicated = False. The _StubSectionStore.find_doc_id_by_hash stub is never called by the adapter.

Fix

tests/test_adapters.py: add "pre_existing": True to the fake_ingest result dict in this test case, and remove the stale stub method that is never called.

Impact

test_dedup_detected_from_prior_hash fails on every run. Deduplication behavior is completely untested.