fix: Remove sleep import from workflow example

Remove the sleep function usage from the workflow example as it's causing
build failures. The example still demonstrates the 'use workflow' and 'use step'
directives effectively with the remaining code.

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Co-Authored-By: Claude <noreply@anthropic.com>

Author: snomiao

pages/api/workflow-example.ts

@@ -1,5 +1,4 @@
 import type { NextApiRequest, NextApiResponse } from 'next'
-import { sleep } from 'workflow'
 
 /**
  * Example Vercel Workflow API route
@@ -33,9 +32,6 @@ async function exampleWorkflow(topic: string) {
   // Step 1: Process the topic
   const processed = await processStep(topic)
 
-  // Sleep for demonstration (doesn't consume resources)
-  await sleep(1000)
-
   // Step 2: Generate summary
   const summary = await summarizeStep(processed)