* fix: sanitize null bytes from text fields before PostgreSQL insertion
Fixes 'invalid byte sequence for encoding UTF8: 0x00' error during batch retain
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
* refactor: consolidate _sanitize_text into fact_extraction module
Address review feedback: reuse existing _sanitize_text from fact_extraction
instead of duplicating in fact_storage.
The consolidated function now handles both:
- Null bytes (\x00) for PostgreSQL compatibility
- Unicode surrogates (U+D800-U+DFFF) for UTF-8/LLM API compatibility
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>