feat: post commit comment when benchmark APK is ready

Adds a GitHub Script step that comments on the commit with a direct
link to the workflow artifacts, making it visible in PRs and branch
pages.

https://claude.ai/code/session_013hcKzBgJgfsrArSgTTGNEk

.github/workflows/build-benchmark-apk.yml

@@ -37,7 +37,20 @@ jobs:
         run: ./gradlew assemblePlayBenchmark
 
       - name: Upload Play Benchmark APK
+        id: upload
         uses: actions/upload-artifact@v6
         with:
           name: Play Benchmark APK
           path: amethyst/build/outputs/apk/play/benchmark/amethyst-play-universal-benchmark.apk
+
+      - name: Comment on commit with APK link
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const runUrl = `${context.serverUrl}/${context.repo.owner}/${context.repo.repo}/actions/runs/${context.runId}`;
+            await github.rest.repos.createCommitComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              commit_sha: context.sha,
+              body: `📦 **Benchmark APK ready!**\n\nDownload it from the [workflow run artifacts](${runUrl}#artifacts).`
+            });