fix(falkor): strip nul bytes from parameters

[he-yufeng]

Summary

Fixes #1525.

FalkorDB rejects query parameters that contain embedded NUL bytes, and the failure happens before the query body runs. Ingested text from PDFs/PPTX can contain stray \x00, so a single bad string can make a whole bulk save query fail.

This strips NUL bytes from FalkorDB query parameters before calling the FalkorDB client. The cleanup is recursive for dict/list/tuple values and is applied in both driver paths that send params:

• FalkorDriver.execute_query(...)
• FalkorDriverSession.run(...), including list-of-query batches

Valid strings are unchanged; only \x00 is removed.

To verify

• $env:DISABLE_KUZU='True'; <pytest bootstrap>; pytest tests/driver/test_falkordb_driver.py::{new and adjacent tests} -q -> 4 passed
• python -m py_compile graphiti_core\driver\falkordb_driver.py tests\driver\test_falkordb_driver.py
• python -m ruff check graphiti_core\driver\falkordb_driver.py tests\driver\test_falkordb_driver.py
• python -m ruff format --check graphiti_core\driver\falkordb_driver.py tests\driver\test_falkordb_driver.py
• git diff --check

Note: this Windows environment has another editable checkout exposing a top-level tests package, so I used a small bootstrap to point tests at this repository before invoking pytest. DISABLE_KUZU=True avoids importing the optional Kuzu driver for these Falkor-only unit tests.

[prasmussen15]

Hi @he-yufeng — thanks for this fix! 🙏
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