ci(benchmark): copy report to GITHUB_STEP_SUMMARY

Author: claude

ci/github-actions/report-benchmark-result-pr.ts

@@ -1,6 +1,6 @@
 import { getOctokit, context } from '@actions/github'
 import console from 'console'
-import { readFileSync } from 'fs'
+import { appendFileSync, readFileSync } from 'fs'
 import process from 'process'
 import { Item as RegressionItem, collectRegressions } from './benchmark/collect-regressions'
 import { SelfBenchmarkCategory, parseSelfBenchmarkCategory } from './benchmark/matrix'
@@ -69,6 +69,11 @@ async function main() {
     reportBody,
   ].join('\n')
 
+  const stepSummaryPath = env.load('GITHUB_STEP_SUMMARY', '')
+  if (stepSummaryPath) {
+    appendFileSync(stepSummaryPath, overallReport + '\n')
+  }
+
   const auth = env.load('GITHUB_TOKEN')
   const github = getOctokit(auth).rest