Macro impl_sdk_model_provider 

macro_rules! impl_sdk_model_provider {
    ($provider:ty) => { ... };
}

Implements rho_sdk::provider::ModelProvider for an application transport that already exposes inherent model_identity, complete_turn, and stream_turn methods.

Streaming buffers same-poll callback bursts, then applies the SDK event channel’s async backpressure before polling the provider again.