[UIK-3788]/unit tests

[Valeria-Zimnitskaya]

Motivation and Context

This PR does not change production component behavior. The changes are focused on unit tests, shared test helpers, CI setup, and test documentation.

Summary

Main changes:

• Added shared data-ui-name unit test coverage for many components.
• Replaced old generic shared tests for className and ref with a narrower shouldHaveDataUiName helper.
• Replaced direct DOM click usage in unit tests with Testing Library/user-event interactions where possible, so tests behave closer to real user actions.
• Moved generic root behavior checks to core tests, where this behavior is actually implemented.
• Added a unit test coverage map to document which component contracts are covered and which ones need local tests.
• Added a small canvas mock for JSDOM, so components that measure text do not print canvas.getContext errors during unit tests.
• Added core utility tests for accessible name and label detection helpers.
• Cleaned up several unit tests to reduce noisy React/JSDOM warnings and make tests closer to real user behavior.

CI and test setup

• Unit tests now run directly with Vitest in CI instead of using the Playwright Docker setup.
• Removed the old VoiceOver test setup because we no longer use VoiceOver tests.
• Kept NVDA test support and updated docs to describe NVDA instead of VoiceOver.
• NVDA CI setup is adjusted to use Node 24.15.0 and install only Firefox.  Because of issues [Regression]: Browsers install stuck on Playwright < 1.60.0 microsoft/playwright#40998
  Node.js 24.16.0: Playwright browser context teardown hangs (regression from 24.15.0) nodejs/node#63495
  playwright install hangs on Node 24.16+ — bump pinned playwright from ^1.58.2 to ^1.60.0 garrytan/gstack#1703

How has this been tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• Nice improve.

Checklist:

• I have updated the documentation accordingly.
• I have added new tests on added of fixed functionality.

[Valeria-Zimnitskaya]

@ilyabrower could you review please
Also i fixed here setup for NVDA but i need help with Build(?) nvda - they fail https://github.com/semrush/intergalactic/actions/runs/27132209994/job/80076217614?pr=2939