Hosted browser commands reject run responses containing expiresAt

[rishabhraj36]

Problem

Webcmd Cloud can include an optional run.expiresAt timestamp in hosted browser responses. The CLI runtime validator currently permits only executionId, session, profile, and liveViewUrl, so it rejects the otherwise-valid response with Webcmd Cloud returned an invalid browser run response.

This causes hosted browser commands—and consequently browser evals using the hosted runtime—to fail even though the cloud execution succeeded.

Expected behavior

The hosted client should accept an optional string-valued run.expiresAt field while remaining compatible with responses that omit it. Non-string values should still be rejected as protocol errors.

Proposed fix

• Add optional expiresAt?: string to HostedBrowserRunResponse.run.
• Permit and validate expiresAt in isHostedBrowserRunPayload.
• Add regression coverage for valid string and invalid non-string values.