add closure comment in sleep test helper (#1071)

Per TooTallNate's review on #1055: the setupWorkflowContext helper
has a circular reference where ctx.onWorkflowError is accessed via
closure before it's defined on the object. Add a clarifying comment.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: pranaygp

packages/core/src/workflow/sleep.test.ts

@@ -19,6 +19,7 @@ function setupWorkflowContext(events: Event[]): WorkflowOrchestratorContext {
   const workflowStartedAt = context.globalThis.Date.now();
   const ctx: WorkflowOrchestratorContext = {
     globalThis: context.globalThis,
+    // ctx.onWorkflowError is accessed via closure — it's defined below on the same object
     eventsConsumer: new EventsConsumer(events, {
       onUnconsumedEvent: (event) => {
         ctx.onWorkflowError(