Copilot auto model selection with task intent [GA]

### Value Prop

Copilot intelligently routes requests to the best model for a developer's specific task, allowing them to benefit from improved service reliability and less rate limiting, all without the cognitive load of model selection. Auto continues to align with model policies and provides discounted model rates for paid plans, providing cost optimization alongside performance.

### Expected Outcome

Developers get faster, more relevant results without needing to choose models manually, increasing productivity and consistency across use cases. Organizations benefit from simplified adoption, improved experience at scale, and clearer value realization through smart, cost-aware routing.