ci: Add unit tests and codecov integration with Vitest

[Copilot]

Implements comprehensive unit tests for the library using Vitest and integrates codecov for coverage tracking.

Test Infrastructure

• Vitest configuration with @analogjs/vite-plugin-angular for Angular support
• Test job in CI workflow runs before publish, blocks on failure
• Codecov upload with fail_ci_if_error: false to avoid blocking on service issues
• lcov reporter for coverage data

Test Coverage

Achieves 100% coverage across all library components:

NgxBackButtonService (11 tests)

• Navigation history tracking and back() behavior with/without history
• Config precedence (child overrides root) and error handling

NgxBackButtonDirective (6 tests)

• Host listener integration and fallback parameter passing
• Config injection from hierarchical DI

Provider Functions (6 tests)

• provideNgxBackButton() and provideNgxBackButtonChild() configuration

Testing Framework Migration

• Migrated from Karma/Jasmine to Vitest
• Converted all test files to Vitest syntax (vi.fn(), vi.spyOn())
• Added test-setup.ts for Angular testing environment initialization
• Test commands: npm test (watch mode), npm run test:ci (coverage), npm run test:ui (UI mode)

Documentation

• Codecov badge and test commands in README
• Development section with Vitest instructions

CI Changes

• New test job runs on push and pull requests
• publish job depends on test passing
• Workflow permissions properly scoped (contents: read for test job)

Original prompt

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This section details on the original issue you should resolve

<issue_title>ci: codecov</issue_title>
<issue_description>## Description
Implement unit test & bind it with codecov</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes ci: codecov #3

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[rbalet]

Please, do the migration to use vitest instead.

[Copilot]

Please, do the migration to use vitest instead.

Migration to Vitest completed in commit 95d97db. All 23 tests passing with 100% code coverage maintained. The changes include:

• Removed Karma/Jasmine dependencies and configuration
• Added Vitest with @analogjs/vite-plugin-angular for Angular support
• Converted all test files from Jasmine to Vitest syntax
• Updated test scripts: npm test (watch mode), npm run test:ci (coverage), npm run test:ui (UI mode)
• CI workflow remains compatible with the new test command

[github-actions]

🎉 This PR is included in version 21.1.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀