Add automated screenshot generation for the README

[Codex723]

Summary

Add a script (Playwright) that captures fresh screenshots of key pages for the README, so docs don't go stale as the UI evolves.

Difficulty

Intermediate — estimated effort: ~1-2 days. Labels: devops, documentation, intermediate

Where to Work

• See relevant files referenced in the description above.

How to Approach This

1. New GitHub Actions workflows go in .github/workflows/ — create the directory if it doesn't exist yet.
2. Keep each workflow focused on one concern (lint, test, contract-CI, etc.) rather than one giant workflow file.
3. Test the workflow logic locally where possible (e.g. run the same npm/cargo commands you're putting in the YAML) before pushing, since Actions minutes are limited.
4. Once merged, confirm the workflow actually triggers correctly on a follow-up PR (check the Actions tab).

Acceptance Criteria

• Workflow/config file added or updated as described.
• Verified the workflow triggers and passes on an actual PR (not just YAML that looks correct).
• Documented in README.md or CONTRIBUTING.md if it changes the contributor workflow.
• No secrets or credentials committed directly into workflow files (use GitHub Actions secrets).

Notes for Contributors

Comment on this issue before starting so it can be assigned to you and duplicate work is avoided. If the described approach doesn't quite fit once you're in the code (e.g. the file has moved, or there's a cleaner way to do it), that's fine — leave a comment explaining the deviation in your PR description rather than silently changing scope.