fix: skip invalid Neo4j embeddings in similarity search

[he-yufeng]

Summary

• fixes [BUG] edge_similarity_search crashes on edges with null/invalid fact_embedding #1328
• skip Neo4j nodes, edges, and communities whose embedding is null or has a different length than the search vector before calling vector.similarity.cosine
• adds a focused query-construction regression test so the guard stays before the cosine call

Tests

• python -m py_compile graphiti_core\driver\neo4j\operations\search_ops.py tests\utils\search\test_search_security.py
• python -m ruff check graphiti_core\driver\neo4j\operations\search_ops.py tests\utils\search\test_search_security.py
• git diff --check
• pytest target: 11 passed, 1 warning

Note: the pytest command had to remove unrelated editable checkout paths from sys.path because this Windows environment has other local repos exposing a top-level tests package.

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[he-yufeng]

I have read the CLA Document and I hereby sign the CLA behalf on myself, e-mail: [email protected] .

[he-yufeng]

Rebased this onto the current main branch and kept both the upstream FalkorDB group-id regression tests and this PR's Neo4j invalid-embedding guards.\n\nLocal validation:\n- python -m py_compile graphiti_core\driver\neo4j\operations\search_ops.py tests\utils\search\test_search_security.py\n- python -m ruff check graphiti_core\driver\neo4j\operations\search_ops.py tests\utils\search\test_search_security.py\n- python -m ruff format --check graphiti_core\driver\neo4j\operations\search_ops.py tests\utils\search\test_search_security.py\n- targeted pytest for the Neo4j/FalkorDB search-security cases: 6 passed, 7 deselected\n- git diff --check origin/main..HEAD\n\nThe first direct pytest attempt in my global Windows environment picked up another installed package named tests; rerunning with the repo's tests package isolated passed.

[he-yufeng]

I have read the CLA Document and I hereby sign the CLA behalf on myself, e-mail: [email protected]

[he-yufeng]

I have read the CLA Document and I hereby sign the CLA on behalf of myself, e-mail: [email protected]

[he-yufeng]

I have read the CLA Document and I hereby sign the CLA behalf on myself, e-mail: [email protected]