Export a public reconnect/retry signal on the TypeScript SDK

Headless embedders of @cursor/sdk set local.enableAgentRetries: true (the default for this posture) so stalled transport recovers automatically. The SDK does not export reconnect or retry state: there is no public onConnectionStateChange, no stream message, and no status value for RETRYING.

Internal machinery already exists (stall detector, onConnectionStateChange with reconnecting / connected, transport-retry counters). It is not on the public TypeScript surface.

Without that signal, an embedder's idle timeout cannot distinguish model silence from an in-progress SDK reconnect. Idle kills then look like a dead model in post-mortems even when the SDK was retrying.

Please export the existing internal stall detector / connection-state hook (for example onConnectionStateChange and/or a stream status for retrying) so embedders can keep transport retries enabled and still observe them.

Start by tracing the internal stall detector, the existing onConnectionStateChange hook, and the transport-retry counters in the TypeScript SDK. Define and expose a public reconnect/retry signal, then verify that an embedder can distinguish model silence from an in-progress retry while local.enableAgentRetries remains enabled.