@playwright/test was missing from devDependencies, causing the
'Install Playwright browsers' step to fail. Added it alongside
the e2e npm script so the reusable workflow can run playwright test.
- Adds e2e/auth.setup.ts, e2e/tns-csi.spec.ts with waitForSidebar helper
- Adds playwright.config.ts, scripts/deploy-e2e-headlamp.sh, scripts/teardown-e2e-headlamp.sh
- Adds .github/workflows/e2e.yaml
- Plugin settings test waits for list before searching