Add personality system using markdown files
- Created personalities/ directory with example personalities
- phi.md: Explores consciousness and integrated information theory
- default.md: Simple helpful assistant
- Load personality from markdown file specified in PERSONALITY_FILE env var
- Falls back to default if file not found
- Updated tests to clarify AT Protocol mention handling
- Removed obsolete BOT_PERSONALITY string config
This allows rich, multi-paragraph personality definitions that would be
awkward to store in environment variables.
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>