Preserve late events after continue-as-new

[berndverst]

Summary

• extract the TaskOrchestrationContextWrapper late-external-event forwarding change from Harden gRPC worker and client against silent disconnects #708 into its own PR
• preserve late-arriving external events when ContinueAsNew has already been scheduled with preserveUnprocessedEvents enabled
• add focused wrapper tests for the ContinueAsNew forwarding behavior

Why

After ContinueAsNew is scheduled with event preservation enabled, late external events should be forwarded to the next execution instead of being buffered on the current wrapper instance that is about to be discarded.

Validation

• dotnet test .\test\Worker\Core.Tests\Worker.Tests.csproj --filter "TaskOrchestrationContextWrapperTests"

[Copilot]

Pull request overview

This PR updates the worker shim’s TaskOrchestrationContextWrapper to ensure late-arriving external events are forwarded to the next execution after ContinueAsNew has been scheduled with PreserveUnprocessedEvents enabled, and adds a focused regression test for that behavior.

Changes:

• Track whether ContinueAsNew(...PreserveUnprocessedEvents=true) has been scheduled, and forward late external events via SendEvent instead of buffering them on the soon-to-be-discarded wrapper.
• Refactor buffered-event forwarding into a helper method reused by both “drain buffer” and “late event” paths.
• Add a wrapper test that simulates a late external event after ContinueAsNew and validates an event is sent.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/Worker/Core/Shims/TaskOrchestrationContextWrapper.cs	Adds state + forwarding logic so late external events are sent to the next execution after ContinueAsNew with preservation enabled.
test/Worker/Core.Tests/Shims/TaskOrchestrationContextWrapperTests.cs	Adds a test exercising the late-event forwarding behavior using a tracking inner context and reflection to invoke CompleteExternalEvent.