[rush-daemon] Add concurrency regression test for serialized invalidation reconciliation

[Copilot]

This addresses the review feedback to verify WorkspaceEngineComponentFactory reconciliation behavior under concurrent calls. The test suite previously validated reconciliation outcomes but did not assert queue/serialization guarantees that protect snapshot handoff and ordering.

• What changed

  • Added a focused test in WorkspaceEngineComponentFactory.test.ts that:
    • blocks the first getInputsSnapshotAsync() call,
    • starts a second reconcileInvalidationsAsync() before the first completes,
    • asserts the mapper is not invoked early for the second reconciliation,
    • asserts the second mapper invocation receives the first reconciliation’s snapshot as currentInputsSnapshot,
    • verifies sequence progression across the two reconciliations.

• Why this matters

  • Confirms the reconciliation tail queue is actually enforcing serialized execution, not just producing correct results in non-concurrent scenarios.

const firstReconciliationPromise = reconcileAsync();
invalidations.invalidate('libraries/b/src/index.ts');
const secondReconciliationPromise = reconcileAsync();

await Promise.resolve();
expect(mapInvalidationsToOperationsAsync).not.toHaveBeenCalled();

finishFirstSnapshot?.();

const firstResult = await firstReconciliationPromise;
await secondReconciliationPromise;

expect(mapInvalidationsToOperationsAsync.mock.calls[1][0].currentInputsSnapshot)
  .toBe(firstResult.inputsSnapshot);