test(frontend): add unit testing with Vitest and CI integration

[ivanskv2000]

✨ What’s Changed?

• Integrated Vitest for fast and efficient unit testing.
• Updated the GitHub Actions workflow to include a new test job.
• Added initial unit tests for parseApiError and useEnhancedToast.

📂 Scope

• frontend
• backend
• common/shared
• CI/config

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud