feat: Add Vitest testing framework for frontend

[singhxabhijeet]

Resolves #42

This PR introduces an automated testing framework for the frontend extension using Vitest, ensuring code quality and preventing regressions.

Changes Made:

• Testing Framework: Added Vitest and jsdom to the frontend package and created a vitest.config.js file.
• Initial Unit Tests: Created the first test file (cache.test.js) to validate caching logic and mock the Chrome Storage API.
• CI Automation: Created a new workflow (.github/workflows/test.yml) that automatically runs npm test on every pull request to the main and develop branches.

Please enable a branch protection rule for the main and develop branches with the following setting:

• ✅ Require status checks to pass before merging
  • Select the frontend-tests job as a required check.

This will ensure the long-term stability of the project. Thanks!

[Copilot]

Pull Request Overview

This PR introduces Vitest testing framework to the frontend package to enable automated testing and improve code quality assurance. The implementation includes a complete testing setup with mocked Chrome APIs for browser extension testing.

• Added Vitest configuration with jsdom environment for browser-like testing
• Created initial unit tests for cache functionality with Chrome Storage API mocking
• Updated package.json with testing dependencies and npm script

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated no comments.

File	Description
frontend/vitest.config.js	Configures Vitest with jsdom environment and global test utilities
frontend/scripts/cache.test.js	Implements comprehensive unit tests for cache functions with Chrome API mocking
frontend/package.json	Adds Vitest and jsdom dependencies plus test script

Files not reviewed (1)

• frontend/package-lock.json: Language not supported

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[dineshsutihar]

LGTM