Add Comprehensive Testing Infrastructure

[Patrick-Ehimen]

This PR introduces a comprehensive testing suite to the project, significantly improving code quality and
stability. It includes unit, integration, and end-to-end (E2E) tests, along with the necessary
infrastructure and CI/CD integration.

Key Changes

• Testing Frameworks:
  • Vitest for unit and integration tests.
  • Playwright for E2E tests.
  • Vue Test Utils & Happy DOM for component testing.
• CI/CD:
  • A new GitHub Actions workflow (.github/workflows/test.yml) automates testing on every push and pull
    request.
• Initial Tests:
  • Unit tests for the blog API with improved error handling.
  • E2E tests for the homepage, blog, and error pages.
  • Component test stubs for the blog components (with some known issues to be addressed).

How to Test

You can run the new tests using the following commands:

1. Run all tests pnpm test:all
2. Run unit tests pnpm test
3. Run E2E tests pnpm test:e2e

Next Steps

• Fix the failing component tests by improving mocking for Nuxt components and composables.
• Address the timeout issues in the integration tests.

closes #188