Dynamic Model Configuration

The CLI now provides enhanced model selection capabilities with runtime configuration support:

• Statsig Integration: Model configuration now integrates with Statsig for A/B testing and feature flags
• Environment Variable Priority: The ANTHROPIC_MODEL environment variable takes precedence over other configuration methods
• Fallback Chain: Implements a robust fallback mechanism for model selection:

1. Check environment configuration
2. Check process environment variable
3. Use Statsig-provided model
4. Fall back to default model

# Set a specific model via environment variable
ANTHROPIC_MODEL=claude-3-opus-20240229 claude

# The model will persist across sessions if set in config