fix: set instanceId on ActivityResponse in failure path

[YunchuWang]

The activity execution error handler in TaskHubGrpcWorker was not setting the instanceId field on the ActivityResponse when an activity throws an exception. The success path correctly called res.setInstanceid(instanceId), but the catch block omitted it.

This deviates from the .NET SDK behavior, which always sets InstanceId on the ActivityResponse regardless of outcome. The missing field could cause issues with sidecar response routing or logging for failed activities.

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[Copilot]

Pull request overview

Fixes an inconsistency in the worker’s activity completion reporting so that ActivityResponse.instanceId is always populated, matching .NET SDK behavior and preventing missing-instance routing/logging issues on failure.

Changes:

• Set ActivityResponse.instanceId in the activity execution failure path in TaskHubGrpcWorker.
• Add unit coverage to verify instanceId is set for activity success, Error failures, and non-Error throws.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/durabletask-js/src/worker/task-hub-grpc-worker.ts	Ensures ActivityResponse.instanceId is set in the catch/failure branch.
packages/durabletask-js/test/worker-activity-response.spec.ts	Adds tests asserting instanceId is present on ActivityResponse in success and failure scenarios.