Add S3 object expiration and PR comment posting for demo videos (#970)

Demo videos from PR builds now expire after 90 days and are posted
directly to PR threads. Uses object tagging with S3 lifecycle policies
for automatic cleanup.

## Changes

**Workflow** (`.github/workflows/tests.yml`)
- Replace `hkusu/s3-upload-action@v2` with
`ramonpaolo/action-upload-s3@main` for tagging support
- Tag uploaded objects: `expiration=90days`, `Source=github-actions`,
`Type=pr-demo-video`
- Generate unique filenames: `pr-{number}-{timestamp}.gif`
- Post PR comment with embedded video using `actions/github-script@v7`

**Documentation** (`CI_CD.md`)
- S3 lifecycle policy configuration (filters on `expiration=90days` tag)
- IAM permission requirements: `s3:PutObject`, `s3:PutObjectTagging`

## S3 Lifecycle Setup Required

```json
{
  "Rules": [{
    "ID": "ExpirePRDemoVideosAfter90Days",
    "Status": "Enabled",
    "Filter": {"Tag": {"Key": "expiration", "Value": "90days"}},
    "Expiration": {"Days": 90}
  }]
}
```

Apply with: `aws s3api put-bucket-lifecycle-configuration --bucket
<bucket> --lifecycle-configuration file://policy.json`

## Notes

- gh-pages `video.mp4` unaffected (served from GitHub Pages, not S3)
- Existing S3 objects without tags remain unchanged

> [!WARNING]
>
> <details>
> <summary>Firewall rules blocked me from connecting to one or more
addresses (expand for details)</summary>
>
> #### I tried to connect to the following addresses, but was blocked by
firewall rules:
>
> - `https://api.github.com/repos/ramonpaolo/action-upload-s3/tags`
>   - Triggering command: `/usr/bin/curl curl -s REDACTED` (http block)
>
> If you need me to access, download, or install something from one of
these locations, you can either:
>
> - Configure [Actions setup
steps](https://gh.io/copilot/actions-setup-steps) to set up my
environment, which run before the firewall is enabled
> - Add the appropriate URLs or hosts to the custom allowlist in this
repository's [Copilot coding agent
settings](https://github.com/thomasnordquist/MQTT-Explorer/settings/copilot/coding_agent)
(admins only)
>
> </details>

<!-- START COPILOT CODING AGENT SUFFIX -->



<!-- START COPILOT ORIGINAL PROMPT -->



<details>

<summary>Original prompt</summary>

> when a demo-video is generated from a pr, add an expiration of 90 days
to the S3 file and post the video as image to the pr thread.


</details>



<!-- START COPILOT CODING AGENT TIPS -->
---

✨ Let Copilot coding agent [set things up for
you](https://github.com/thomasnordquist/MQTT-Explorer/issues/new?title=✨+Set+up+Copilot+instructions&body=Configure%20instructions%20for%20this%20repository%20as%20documented%20in%20%5BBest%20practices%20for%20Copilot%20coding%20agent%20in%20your%20repository%5D%28https://gh.io/copilot-coding-agent-tips%29%2E%0A%0A%3COnboard%20this%20repo%3E&assignees=copilot)
— coding agent works faster and does higher quality work when set up for
your repo.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: thomasnordquist <7721625+thomasnordquist@users.noreply.github.com>

.github/workflows/tests.yml

@@ -67,20 +67,52 @@ jobs:
         run: yarn ui-test
       - name: Post-processing
         run: ./scripts/prepareVideo.sh
-      - uses: hkusu/s3-upload-action@v2
-        id: upload # specify some ID for use in subsequent steps
+      - name: Generate unique filename
+        id: filename
+        run: |
+          TIMESTAMP=$(date +%Y%m%d-%H%M%S)
+          FILENAME="pr-${{ github.event.pull_request.number }}-${TIMESTAMP}.gif"
+          echo "filename=${FILENAME}" >> $GITHUB_OUTPUT
+      - name: Upload to S3 with expiration tag
+        id: upload
+        uses: ramonpaolo/action-upload-s3@main
         with:
-          aws-access-key-id: ${{ vars.AWS_KEY_ID }}
-          aws-secret-access-key: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
-          aws-region: 'eu-central-1'
-          aws-bucket: ${{ vars.AWS_BUCKET }}
-          file-path: './ui-test.gif'
-          content-type: image/gif
-          output-file-url: 'true'
+          AWS_BUCKET_NAME: ${{ vars.AWS_BUCKET }}
+          AWS_REGION: 'eu-central-1'
+          AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+          AWS_ACCESS_KEY_ID: ${{ vars.AWS_KEY_ID }}
+          local_path_upload: './ui-test.gif'
+          bucket_path_upload: '/'
+          name_to_save_on_s3: ${{ steps.filename.outputs.filename }}
+          tags: 'expiration=90days&Source=github-actions&Type=pr-demo-video'
+      - name: Generate file URL
+        id: fileurl
+        env:
+          AWS_BUCKET: ${{ vars.AWS_BUCKET }}
+          FILENAME: ${{ steps.filename.outputs.filename }}
+        run: |
+          FILE_URL="https://${AWS_BUCKET}.s3.eu-central-1.amazonaws.com/${FILENAME}"
+          echo "file-url=${FILE_URL}" >> $GITHUB_OUTPUT
+          echo "Uploaded to: ${FILE_URL}"
       - name: Show URL
-        run: echo '${{ steps.upload.outputs.file-url }}'
+        run: echo '${{ steps.fileurl.outputs.file-url }}'
         id: artifact-upload-step
-      - run: echo '<picture><img src="${{ steps.upload.outputs.file-url }}"></picture>' >> $GITHUB_STEP_SUMMARY
+      - run: echo '<picture><img src="${{ steps.fileurl.outputs.file-url }}"></picture>' \
+          >> $GITHUB_STEP_SUMMARY
+      - name: Post video to PR
+        uses: actions/github-script@v7
+        env:
+          VIDEO_URL: ${{ steps.fileurl.outputs.file-url }}
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            const videoUrl = process.env.VIDEO_URL;
+            github.rest.issues.createComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              body: `## 🎬 Demo Video Generated\n\n![Demo Video](${videoUrl})\n\n_This video will expire in 90 days._`
+            });
 
   test-browser:
     runs-on: ubuntu-latest