This fixes the asyncpg.exceptions.CharacterNotInRepertoireError that occurs
when tool returns contain null bytes (0x00), which PostgreSQL TEXT columns
reject in UTF-8 encoding.
Changes:
- Add sanitize_null_bytes() function to recursively remove null bytes from strings
- Update json_dumps() to sanitize data before serialization
- Apply sanitization in converters.py for tool_calls, tool_returns, approvals, and message_content
- Add comprehensive unit tests
Fixes#8014🤖 Generated with [Letta Code](https://letta.com)
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Co-authored-by: Letta <noreply@letta.com>
Co-authored-by: Kian Jones <11655409+kianjones9@users.noreply.github.com>
