Playwright E2E tests #10
Description
Summary
We should add a Playwright e2e suite to catch UI + control-plane regressions, especially for Design/Monitor view (create/edit sessions, graph rendering, inspector/yaml sync, telemetry/metrics updates).
Scope
- Add Playwright infra in e2e/ (deps, config, test runner, CI wiring).
- Provide stable test selectors (data-testid) for critical UI elements (minimize brittle CSS/text selectors).
- Add a small set of high-value smoke/regression tests focused on:
- Design view graph editing + YAML sync
- Monitor view session lifecycle + live updates
- Run in CI on every PR; upload traces/screenshots/videos on failure