.NET: feat: adds the executorId as an additional property when running the workflow as agent in dotnet

[Vincent Biret (baywet)]

fixes #4445

[Copilot]

Pull request overview

Adds workflow executor attribution to streamed .NET agent response updates.

Changes:

• Adds a public executorId metadata key.
• Attaches executor IDs to response updates.
• Adds multi-executor streaming coverage.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
WorkflowAgentAdditionalProperties.cs	Defines the executor ID key.
AgentResponseUpdateEvent.cs	Adds attribution metadata to updates.
WorkflowHostSmokeTests.cs	Tests attribution and metadata preservation.

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[westey (westey-m)]

FYI: If we are unsure about something new that is public we often mark it as experimental, to make sure we can still make changes to it before graduating the feature. We then remove experimental once we are happy with the overall change.
Not sure if that is applicable here, but just an FYI.

[Vincent Biret (baywet)]

Thanks I think Tao Chen (@TaoChenOSU) and Peter Ibekwe (@peibekwe) will be able to inform the design here and whether or not we need to add those experimental aspects.

[Vincent Biret (baywet)]

worth exploring this instead of magic keys in a dictionary

update.RawRepresentation is ExecutorEvent exevt
exevt.ExecutorId

[github-code-quality]

Code coverage overview

Languages: C#

C# / code-coverage/dotnet

main f7a5fcb	feat/workflow-as-age... 6df5254	+/-
86%	86%	0%

View coverage of the 4 most impacted files.

File	main f7a5fcb	feat/workflow-as-age... 6df5254	+/-
/home/runner/wo...SessionStore.cs	100%	53%	-47%
/home/runner/wo...kflowSession.cs	87%	88%	+1%
/home/runner/wo...eUpdateEvent.cs	73%	83%	+10%
/home/runner/wo...esponseEvent.cs	67%	80%	+13%

ℹ️ Calculations represent line coverage. Results may change as calculations are updated.