chore: add Playwright full test coverage

[ghiscoding]

• this PR adds E2E tests for all demos

[github-actions]

🎭 Playwright Summary - Success 🎉

Playwright Report

multiple-select-root@0.0.0 test:e2e:ci /home/runner/work/multiple-select-vanilla/multiple-select-vanilla
playwright test --config playwright/playwright.config.ts

Running 126 tests using 1 worker
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126 passed (2.9m)