Upload demo videos even when UI tests fail

[Copilot]

Demo video recording fails silently when locators timeout or elements aren't clickable, making test failures difficult to debug without visual artifacts.

Changes

Workflow (.github/workflows/tests.yml)

• Mark video generation step as continue-on-error: true with step ID to capture outcome
• Add if: always() to post-processing, uploads, summary, and PR comment steps
• Check file existence before S3 upload to handle partial failures
• Pass test outcome to markdown generator via TEST_STATUS environment variable

Markdown Generator (scripts/generateMarkdownSummary.js)

• Accept optional test status parameter (defaults to success for backward compatibility)
• Show ⚠️ icon and warning note when status is not success
• Handle missing scenes.json gracefully instead of crashing

Behavior

Before: Test fails → no video uploaded → no debugging artifacts

After: Test fails → partial video uploaded → PR comment shows:

## ⚠️ Demo Video Generated (Test Failed)

> ⚠️ **Note**: The demo test encountered errors but videos were still uploaded for debugging. Check the logs for details.

### Full Video
[📥 Download Full Video (MP4)] | [GIF]

Matches existing demo-video-mobile job behavior.

Original prompt

update the demo video workflow so the video is also uploaded if there was an error during the recording (eg. A locator failed or a fun element could not be clicked)

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