fix: update UI deps

[mdeliatf]

What does this PR do?

This PR updates and improves several aspects of the traefiklabs-hub-button-app development tooling:

• Upgrades Yarn to v4.9.2;
• Updates ESLint-related dependencies and Prettier to compatible versions, respecting semantic versioning (no major version bumps when applicable). In particular, the version range of eslint-config-prettier has been adjusted to avoid accidentally resolving to a version that was affected by CVE-2025-54313;
• Adds a missing peer dependency: @testing-library/dom;
• Updates caniuse-lite to the latest available version;
• Adds lint and format npm scripts for improved developer experience.

Motivation

These updates keep the traefiklabs-hub-button-app tooling aligned with compatible, stable dependency versions, improving consistency, compatibility, and maintainability without risking breaking changes due to major version upgrades (except for Yarn, which has been explicitly upgraded).

Although the vulnerable versions of eslint-config-prettier have been removed from the npm registry, the ^ version range previously declared in the package.json could have led to their installation in some edge cases - unlikely, but still possible. Updating the version constraint eliminates this risk entirely.

The ESLint-related dependencies and Prettier have been updated to versions compatible with the current setup to ensure smooth integration with existing configurations.

Finally, the added lint and format scripts simplify running code quality and formatting commands, enhancing the developer workflow.

Fix https://github.com/traefik/hub-issues/issues/2148