Replace hardcoded DEEPSEEK_API_BASE/DEEPSEEK_MODEL env vars in _get_deepseek_brain() with new BRAIN_* environment variables: - BRAIN_API_BASE (default: http://localhost:11434) - BRAIN_MODEL (default: gpt-oss:20b) - BRAIN_TEMPERATURE (default: 0.3) - BRAIN_MAX_TOKENS (default: 1024) - BRAIN_TIMEOUT (default: 30.0) All params now passed directly to DeepSeekConfig constructor.